Get the Shark Costume from Joe, then go right into the break room. There are some Biologists here. Afterwards, go to every Biologist in the large room that leads into the cafeteria.
In the "World of Kelp" level. stop the Kelps that your sons shoot at you with an otter figure. After that mini-game ends, pick up the otter's head and put it on your head.
At the start of the last chapter, "Hot Concessions", allow the game to idle until you die one hundred times.
Get the captain's uniform, then return to the ship and approach every sailor. Make sure they talk to you and not with each other. You also have to talk to the sailor who you stole the coffee from after going back over the beam crane.
Play "Deep Dark Sea". After you get the shake light, Stacy will ask for it when you find the biologist. Before giving her the shake light, continue walking ahead to find the jellyfish collection.