Undersea Dream is a water-themed board in Mario Party 5. It is based on dreams of living underwater and such. The board is made of two reefs at the bottom of the sea.
The board starts the players on the left reef traveling clockwise. The player gets the choice early in the board to go along the long upper path with two Happening spaces but being forced to go to the other reef or take the shorter lower path and then being given the option to loop around.
As players cross to the second reef, they are given a choice to go on the upper path and get a capsuleor take the shorter lower path. The paths meet up at the bottom of this reef which has two happening spaces. The player is then given the choice to return to the first reef or loop around the lower path again.
The happening spaces with at the bases of the reefs with the logs trigger a manta that the players can ride and collect coins along the way,
The happening space next to the sunken ship causes a dolphin to take the player to another part of the board.
The happening space next to the whale launches the player closer to a star.
The happening space at the bottom of the second reef causes a Cheep-Cheep to come and play a shell game with the player. If the player chooses the one with the Capsule, they get that capsule while chooses the boot gets them nothing.