To find the first Deadpool floatie, head to the very back of The Yacht and land on the middle deck.
From there, head into the room on the right-hand side of the deck and you'll find the floatie on the ground inside.
For the second Deadpool floatie, you need to head to the lowest level of the main part of The Yacht. The easiest way to find this area is to keep to the water level section of The Yacht and then head through the door, which sits between two large sections of piping.
Down in these depths, you'll find the floatie next to a small green screen, with a chest sitting in front of it.
For the third and final Deadpool floatie, head to where the Deadpool choppa sits at the front end of The Yacht.
Once you're there, look to your left and you'll see a small bedroom area inside one of the shipping containers. Inside this made up room, you'll find the Deadpool floatie.
There may be other Deadpool floaties hiding out in The Yacht, but you only need to find these three to complete the challenge. Just remember to search them or else it won't count!