Koopa Beach 1
From the Super Mario Wiki
Koopa Beach 1 is the first course of the Star Cup in Super Mario Kart. It is a very short course and takes place on a set of small islands. Its hazards are Cheep-Cheeps and green sections of the beach which slow karts down. Karts can drive in the light-blue water, which will make them slow down a bit, but will sink if they go to the dark blue water. There is an extra Item Box a bit off the track, which is quite easy to reach though.