Aside from the pet crab, you might get some Roblox Islands items like the Pirate Chandelier, Puffer Fish, Pirate Ship or even a Shark. Each chest that you open gives you a random shot at a prize.

Fish in the whirlpool to get Isonade (Image via Roblox) Isonade is available at any time and during any weather and season. To increase the chances of catching the Mythical fish, use the Truffle Bait.