The Tide Pools are a location in Freddi Fish 2: The Case of the Haunted Schoolhouse.
This location is to the northwest of the school. You need it to go to the other side if you need to get purple sea urchins (one of them is on a rock cliff) in the Pulley storyline and/or go to Mr. Triplefin to get the combination to the trophy case lock in the Mock-Stop-Mibble-Bock-Wopper-Bopper storyline.
To do that you should click the nearest pool to ask Freddi and Luther to jump there. If it's too far, they won't be able to do it. If, after you have reached the opposite side for the first time during your current playthrough, you don't want to spend time clicking the tide pools, just click the faraway side, and fish will reach it jumping to the pools in sequence. The first time you click the opposite side, Freddi and Luther will comment they cannot jump that far.