[2] Unlike its predecessor Evolution, in which players execute their turns in shared phases, in Oceans players take individual turns to create species by assembling trait cards.

Each turn, the player uses one card to either evolve an extant species, to create a new one, or to migrate fish from one ocean box to another.

[4] The player with the most collective fish tokens in their score pile and on their species boards wins the game.

[4] The company consulted with Brian O'Neill, a marine biologist at the University of Wisconsin–Whitewater, to establish the scientific background for the game.

[2] In a review for Science News, Mike Denison states that the game's design "masterfully translates the wonders and complexities of marine ecology to a tabletop setting" and the gameplay results in a "(mostly) scientifically accurate experience".

[1] In a review for Board Game Quest, Tony Mastrangeli described the pace of play as a "slow build up", and slower than its predecessor Evolution.