What do you think of creatures actually using currents to their advantage? Right now, underwater rapids feel a bit stagnant. It would be amazing if some rare fauna or just about any creature near a current would actively hop into it when chased to escape the player, or just casually use them to navigate.
Taking it a step further: what about a “current-trap” creature? It could anchor itself and wait for prey (or the player) to get swept in, catching them with net-like appendages or a massive open mouth.
Imagine a new Leviathan hidden inside a structure that looks exactly like a cave entrance. As you approach, the Leviathan actively generates a powerful underwater rapid / suction to pull you straight into its jaws. It would make exploring currents way more intense and terrifying!
Actually a classic