Complete all side quests. One way or another.

Research all pots.

Visit every dock in the game.

Research all engines.

Use Mixed Bait to attract 3 different species to a single spot.

Have a combined engine speed of 75kn.

Use Atrophy on a fishing spot a long way away.

Hear a Foghorn echo.

Catch 150 fish in trawl nets.

Give up the Pocket Watch.

Research all nets.

Relinquish the Necklace.

Research all rods.