Fisher King! Trophy
Swam a Marathon!
You unlock the ability to swim in the fifth world, Sea of Serendipity.
Exactly the same as "Sprinter!", only instead of running, this trophy requires you to swim a total distance of a "marathon".
By swimming, we mean diving in the water, swimming. Doggy paddling on the top of water does not count. As you'll be replaying the levels in the Sea of Serendipity for Electoons and and Time Trials, you will again, unlock this trophy naturally.