From the Super Mario Wiki
Dolphin Shoals is second race track in the Star Cup of Mario Kart 8 and Mario Kart 8 Deluxe. This course takes place on a beach with dolphins swimming around and an undersea cave with a large Unagi. The dolphins here appear as in Mario Kart Arcade GP DX. Multiple dolphin shaped hills can be seen in the background.
The course starts in a lake. There is a left turn coming out of the lake and then leading back underwater with three ramps in the section. One on the left, one on the right, and one straight ahead. There are rings where the players jump over the ramps, where Dolphins also jump through. After that section, still underwater, there is a left turn leading the players to an undersea cave, where two paths split. The left path leads to an area where players float above pipes generating currents keeping the player floating, where they can also perform a trick on. The right path is a shortcut split with two other paths, one with the current-generating pipes going to a platform with a boost platform and one where it leads to a small cave section with two boost platforms.
When the two paths meet, there is a boost ramp where players jump over along with more water bubble pipes, with a big Unagi in front of it. Players can drive over the Unagi's body, where coins appear at the tip of it. If players fall they can just drive under it during the section. After that, players activate the anti-gravity mode and jump off a ramp out of the cave and goes to a platform held with rocks that is tilted almost sideways. There is another ramp on the track after which there is a gliding section. Players fly over a water rapid then land back on the track where there is a few more turns, going back underwater and leading to the finish line.
Mario Kart Facebook Page: Next stop: Dolphin Shoals – an underwater paradise in Mario Kart 8 where blue Spiny Shells glisten in the sunlight and shortcuts hide behind every reef. 
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