Sirena Beach is a location found on Isle Delfino in Super Mario Sunshine. It is located on the island's south coast, right behind Pinna Park. Its name probably derives from "Sirena", the Italian and Spanish term for "mermaid". It also bears similarity to the term "serene", describing the atmosphere of the beach.
Sirena Beach is famous for being the home of Hotel Delfino, a well-known four-star hotel and seaside resort. The outside of the place features three pools filled with water, torches to illuminate the place at night, two cabanas for refreshments, as well as some terraces for sun-bathing. It is also widely known for its impressive sunsets. The hotel itself features several rooms, a pool room, a fruit bar, restrooms and a big casino which can also be visited. There is also a mazy attic from which more rooms can be accessed. Once Mario entered the hotel, he cannot return to the beach without completely exiting the level. A similar case appears with the casino. The level itself can only be accessed through a red Warp Pipe in Delfino Plaza. Said pipe is blocked by a giant pineapple and the Mario needs to unlock Yoshi first before they can get through the pipe.
Mario always visits Sirena Beach only in the evenings, when the sun is about to set (the only time it can be seen during the day is when it's viewed from Pinna Park). The main problems he has to deal with in this area are a persistent infestation of Boos inside the hotel and hazardous Electric Goop outside the hotel. He also fights against King Boo and Phantamanta here, both being the cause of said problems, respectively.
Most of the episodes take place inside Hotel Delfino; Mario can enter the building by talking to its manager, whom stands in front of the entrance. The Pianta asks for no charge for letting Mario in, but expects him to help the hotel out in return.
The layout of the beach is, if examined closely, identical to the layout of a GameCube controller, if seen from the hotel looking out to the sea. The pools of water represent the , ,, and buttons, a small flame to represent the , the chairs set up beyond that to represent where "Nintendo GameCube" would be printed, and two cabana huts to represent the and .
 Episode 1: The Manta Storm
The first episode of Sirena Beach begins with a shot of its characteristic sunset above the sea. It then cuts to the landside and pans over the area to show that a significant part of the landscape is covered in turquoise-colored Electric Goop. The thick substance has covered some Noki visitors and even the hotel building is obscured by a large puddle of slime shaped like a giant manta. Several Piantas can be seen around the spot where the building went missing, some are employees trying to clean the place while others are infuriated hotel guests. Upon approaching the hotel manager Mario learns that a giant shadow-like creature called Phantamanta appeared at noon, produced all the hazardous Goop and made the hotel vanish. Their conversation is cut short by another appearance of said monster and a boss battle begins.
The orange silhouette slowly approaches the scenery from the beach while leaving a thick trail of the Electric Goop behind. Spraying it with water from F.L.U.D.D. will cause it to emit electric sparks and three direct hits with water will make it split into two. The halves will then act separately and split again after enough hits. Phantamanta must be split four times until its parts can be defeated permanently. The parts creach all over the place and the only safe places are spots with roofs. After all the parts of Phantamanta are in their smallest forms, the orange silhouettes will turn red and actively chase Mario. After Mario defeated every single part of the enemy the hotel will rise from the ground again and a Shine Sprite will appear above the pillar in the center of the level.
 Episode 2: The Hotel Lobby's Secret
The second episode sets in with a shot from above the big hotel and then slowly pans down to show its front side. The masses of turquoise slime from the previous episode have disappeared but the hotel is still closed due to a ghost-infestation, much to the dismay of the guests. The hotel manager asks Mario to enter the hotel to get rid of the plague. The cause of the trouble appears to be a golden boo statue that appeared at the top floor. Due to the emergency situation however, the staircases leading to said floor have been sealed off and the players have to find an alternative route. By spraying the Red Boos surrounding the large pillar in the middle of the building with water Mario can build a path to the monument.
After jumping into the statue's mouth Mario will be transported into a secret level. Shadow Mario will then appear and steal F.L.U.D.D., so Mario has only his jumping abilities to get through the obstacle course. The area is filled with Strollin' Stues, Soarin' Stues, Sand Blocks and Brick Blocks. Some of the Brick Blocks in this area contain 1-Up Mushrooms that will give Mario an Extra Life. At the end of the course, he will find a Shine Sprite. After having completed the second episode of Sirena Beach, the players can replay the level and bring F.L.U.D.D. with them to participate in a Red Coin challenge.
 Episode 3: Mysterious Hotel Delfino
The third episode opens with another pan shot from above the hotel. After Mario got rid of most of the ghosts the hotel has reopened and the guests are able to get into the building again. The Doot Doot Sisters also appear from this episode on, performing at the beach. At the front door of Hotel Delfino the hotel manager invites Mario into the building again. Inside the hotel, the players can see the Shine Sprite of this episode sparkling in the pool room at the top floor through a wall of glass. The object is out of their reach however, since a Pianta denies Mario access to the room because of his lack of swimwear. Mario has to find a way to break into the room from the attic. However, the attic is filled with sleeping Boos which cannot be defeated by normal means. Mario has to go back to the reception near the entrance to find a Yoshi Egg which demands a pineapple. Unfortunately, the fruit seller on the other side of the room is currently out of pineapples, so Mario has to search the hotel for the fruit. He can find some by traveling through the hotel guests' rooms. Mario starts by talking to a Pianta outside the bathroom who tells him that there is water damage in there. Mario should go inside and walk to the last stall. From here he can jump up into the tub of the above room. In this room, another Pianta says that she gets a weird vibe from a painting in the room. If Mario sprays it with water, a picture of a Boo is revealed, and he can now travel through the painting to the adjoining room. This room houses two Nokis who are running around, terrified by several Boos in the room. To go to the next room, Mario must spray the closet doors until they all spin around and make a boo picture. They will then open up into the next room, which holds two Red Boos. Mario should spray them and use the platforms they create to travel through a hole in the ceiling. In this room, there is a bookcase that will flip when stayed with water, allowing access to the next room. The room has a poster which can be sprayed to go to an optional room with a Blue Coin. To advance to the next room, Mario must jump on the floor tile that is a slightly different color. The room below has several crates, some of which contain pineapples. Mario can now take one and leave the room to bring it to Yoshi. Now Mario must go to the third floor, enter the open room and jump on the bed to reach the attic. Here he must navigate a maze in search of cracked floor tiles. One of these will lead to the pool when Ground Pounded, allowing Mario to obtain the Shine Sprite.
 Episode 4: The Secret of Casino Delfino
Another pan shot of Hotel Delfino serves as the introduction scene for this episode. The hotel is still open for business and upon approaching the building the hotel manager invites Mario to the casino that has recently reopened. The casino can be found next to the restrooms on the ground floor. It is composed of a big hall filled with slot machines, fountains, a red curtain, and a giant roulette. Using F.L.U.D.D. Mario has to get a row of three lucky sevens on both of the giant slot machines. By successfully doing so the big red curtain will rise and reveal a wall made of sixteen red and yellow panels that flip once they come in contact with water. When all panels are flipped so they show their colored backside, they will form an image of a Shine Sprite and reveal a Warp Pipe leading to a secret area.
On the other side of the pipe Shadow Mario awaits and steals F.L.U.D.D. from Mario. By using his various jumping techniques, Mario has to traverse the obstacle course located in a strange realm filled with seagulls. The obstacle course features glass cubes that attempt to push Mario from platforms, wooden contraptions that move in different ways, and a giant rotating cube that floats above a Bottomless Pit. Also, the glass cubes are able to crush Mario. If Mario is crushed, he will lose a life, regardless of his current health. At the end a Shine Sprite awaits. After having completed this episode, the player can return to this level with F.L.U.D.D. to try winning in a Red Coin challenge.
 Episode 5: King Boo Down Below
The episode opens with the same pan shot like in previous episodes. In front of Hotel Delfino, Mario learns from the manager that the casino was closed after some creepy sounds emerged from the place's basement. The hotel manager sends Mario to investigate and to get rid of what caused the commotion. Upon Mario's arrival, the casino is infested with Boos that disguise themselves as Coins. The Piantas that work here are confused about a tile on the big roulette which suddenly turned to a glowing purple color. A Ground Pound on the glowing tile will cause the contraption to descend into the basement where a boss battle against King Boo will commence.
The battle against the king of Boos takes place on a circular battlefield which is divided into a center area and three rings that rotate around it. The middle ring spins in the reverse direction of the inner and outer ring, making it harder to navigate. Three purple tiles like the previous one can stop the rings' movement temporarily. King Boo hovers above the center area and produces smaller Boos that attack Mario. Spraying him with water will cause him to fetch a giant slot machine and another hit with water makes him activate the machine. There are various possibilities what happens after that, depending on the results of the spin. Three question marks will result in King Boo summoning a bunch of random enemies from any world that will chase Mario. Three coins will make some Coins appear which Mario can use to restore his health. Three Strollin' Stu symbols will summon a horde of Strollin' Stus to King Boo's aid. A mismatch of any symbols will cause King Boo to spit water bubbles which can be popped with F.L.U.D.D. and refill its water tank. The player's objective during this boss fight is to get three pineapple symbols. By doing so, many different fruits will appear. Mario needs to pick up the pepper and throw it at the enemy (any other kind of fruit will only make King Boo mock the player). The boss will then be paralyzed for a moment and can be damaged by throwing any fruit at him. After Mario repeats this attack three times, King Boo is defeated and another Shine Sprite will be revealed. It is also possible to get the 100 coin Shine Sprite in the basement. If the player gets the 100th coin there, the Shine Sprite will appear above the center of the arena, and it can be obtained even while the boss fight is still going on.
Note that when Mario talks to the lodgers inside the hotel in this episode, they give the same dialogue as in Episode 4. This is probably because the main purpose is to go directly to the hotel casino, because there is no need for helpful advice inside the rest of the hotel.
 Episode 6: Scrubbing Sirena Beach
The introduction scene for this episode shows a close-up of a Pianta employee scrubbing the floor and then zooms out to show the area in front of Hotel Delfino. The whole area in front of the building has been defaced by thick Electric Goop which is shaped like a smiling Boo face. Right after entering the level, the hotel manager will talk to Mario and ask him to clean the place. Mario has three minutes to do so, or he will lose an Extra Life. Various barrels filled with water help Mario with this task. After the area is at least 99% clean Mario will obtain a Shine Sprite after talking to the manager once more.
 Episode 7: Shadow Mario Checks In
The seventh episode of Sirena Beach is yet another Shadow Mario challenge, which must be successfully completed to unlock the entrance to Corona Mountain, where Mario will face the final boss. The episode begins normally with the usual pan shot from above the hotel, although two angry Piantas can be seen in front of the building. The hotel has been evacuated because of mysterious incidents that have taken place inside the building. Upon talking to the manager, Mario will learn that a doppelgänger of him has infiltrated Hotel Delfino and is causing trouble. Mario has to chase the enemy through the different floors and spray him with water. Some of the leftover Boos from previous episodes help Shadow Mario by posing as him to confuse the player. The copies are of a lighter color though, and thus can be distinguished relatively easily. It is also possible to defeat all the copies and chase Shadow Mario afterwards to avoid confusion. After some hits with water, Shadow Mario will give up and release a Shine Sprite.
 Episode 8: Red Coins in the Hotel
The eighth and last episode of Sirena Beach sets in with the same cutscene like the previous episodes. Everything seems to have returned to normal and any Goop as well as the Boo infestation has disappeared. The Doot Doot Sisters, while being absent in the previous two episodes, have returned as well, despite their apparent dislike for the circumstances at the place. The hotel manager invites Mario into the hotel once more. In the lobby, he will find a red switch which will initiate a Red Coin challenge. If Mario manages to find a set of eight Red Coins hidden throughout the entire hotel within five minutes, he will be rewarded with another Shine Sprite.
 Episode 9: Red Coins in Boo's Big Mouth
In this episode, Mario must replay Episode 2, though this time he must enter the Boo statue's mouth and collect eight Red Coins. If he manages to collect them all before the 1:30 time limit is up, a Shine Sprite will be revealed.
 Episode 10: Red Coin Winnings in the Casino
In this episode, Mario must replay Episode 4, though this time he must enter the green Warp Pipe at the back of the casino and collect eight Red Coins. If he manages to collect them all before the 1:00 time limit is up, a Shine Sprite will be revealed.
 Blue Coin Locations
The music of Sirena Beach is mostly inspired by Hawaiian music (albeit adjusted to be slightly unsettling). While an upright bass provides a bassline, a steel guitar slides repetitively. Synthesizer and maracas play constantly in the background, while electronic organ and acoustic guitar also contribute to the melody. The theme was composed by Shinobu Tanaka.
 Official Description
The gentle lapping of the sea accompanies spectacular sunsets and romantic dinners beneath starry skies. The four-star Hotel Delfino has it all.
 Names in Other Languages