Each player's bag has 18 identical core discovery tiles as well as up to 3 additional advanced discovery tiles, which depend on the Expedition being played.

Each discovery tiles has an undiscovered (dark background) side and a discovered (light background) side. Only discovered tiles and tokens are scored at the end of the game.

During each round a Discovery token can be flipped over to its "discovered" side if a ship is standing over it as well as tiles that are adjacent to a player's submersible can be flipped during the Submersible phase.