Blooper Beach is one of the seven boards in Mario Party 9. It is set in a tropical ocean, surrounding a few beaches and islands. The mid-boss fort is home to a giant Cheep-Cheep, while the Bowser Gate at the end leads to a fight with Blooper. Most of the board's gimmicks have to do with the sea, and the two boss battles involve accurate use of projectiles to emerge victorious.
The players begin near the shoreline, and move further out to sea towards the mini-boss fort. As the game begins, a Dolphin appears on the board, moving two spaces a turn; a captain who catches up to the Dolphin receives five Mini Stars. After the Dolphin has been passed, it disappears, and a Sushi arrives a few spaces behind the players. Unlike the Dolphin, the Sushi moves four spaces each turn, and it is trying to catch up to the players' vehicle. If the Sushi reaches the vehicle, it will take half of the current Captain's Mini Stars. Afterwards, the Dolphin will appear again. This gimmick ceases once the mini boss fort is reached, after which the Dolphin/Sushi will swim away.
After the mini boss is defeated, players move to the second half of the board. If the Captain lands on an Event Space here, Huckit Crabs will fire Mini Ztars from cannons on a beached ship, transforming all Mini Stars on the board into their negative counterparts. To reverse this, a Captain must land on another Event Space, which causes the Huckit Crabs to transform the Mini Ztars back into Mini Stars.
If the Captain lands on the Unlucky Spaces near the middle of this part of the course, a nearby Blooper statue will trap the vehicle in a giant whirlpool lined with Mini Ztar Spaces and a few Dash Spaces. Players must escape the whirlpool by going along the path until it merges with the main course; however, the whirlpool will pull the vehicle back two spaces at the end of every turn.
Near the end of the board (after the Almost There! event), Captains can land on a special Lucky Space that gives them three Mini Stars and leads them to Star Island. This small landmass has three Dice Spaces, a Dash Space, a Lucky Space, and two clusters of three Mini Stars in a circular path; players take turns moving around the small track, collecting Mini Stars and Dice Blocks. The ultimate goal, however, is to land on the Lucky Space; the Captain who does so gets to collect ten Mini Stars from the center of the island. After the Lucky Space is hit, the vehicle returns to the main course.
At the very end of the course, players reach a large rock formation. Upon passing through the Bowser Gate, they battle a stage boss (Blooper in Solo Mode) for the rest of the Mini Stars in Blooper Beach.
The characters ride a boat on this board. The vehicle available from the start is the Sub Baleen. The Coral Explorer and the Blooper Boat can be purchased from the Museum for 200 Party Points each.
 Sunken Treasure
Sunken Treasure is the Captain Event for this board. In this event, the players leave their team vehicle and board diving platforms filled with Mini Stars. There are two instances of this event, both in the second half of the course; one is set shortly after passing the small island, and the other is set near the end of the lower path in the final split in the course before the end.
Each player will roll a 1-6 Dice Block, a 1-2-3 Dice Block, and a 4-5-6 Dice Block. The captain chooses the order, which is the same for all players. The goal is to reach the top after rolling all three dice, but a player who lands on an Unlucky Space will lose five Mini Stars. The paths are identical for every player other than the captain, who has a path of the same length but with fewer Unlucky Spaces. Every player who reaches the top will earn as many Mini Stars as there are remaining in his or her basket.
The most Mini Stars a single player can earn in this Captain Event is 10 (first time) and 15 (optional second time), and the least is zero.
To defeat Cheep Cheep, players must grab Green Shells as they pass by and throw them at the oversized fish. In the process, they must also evade Cheep Cheep's charge attack; after it loses half of its health, they need to beware of body slams as well.
To defeat Blooper, players must bombard it with their cannons, while simultaneously deflecting the Urchins it throws in return. At half health or less, Blooper's projectiles can rebound after a shot and target a different player; it takes three hits to destroy them.
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