The Atlantic update for Fisch adds the new Grand Reed Bestiary, several fish, and some boats to the game. At the Grand Reef island, talk to the Bubble Mermaid NPC and she'll give you a task to collect three Resin samples; here's how you can obtain this item in Fisch.
Start by getting on your boat and heading into the ocean. When the POI indicators appear on your screen, look for Mushgrove Swamp and head towards it. Drive the boat to the new location and you'll come up on an island covered by tall mushrooms. Pull out your fishing rod and start fishing inside the Mushgrove Swamp in order to catch Resin samples.
Collecting this item is quite challenging because Resin is a secret item with extremely low chances of spawning, and you need to acquire three of these to complete the objective. You can improve your fate of finding a Resin by using rods and baits with high luck statistics. Furthermore, if you don't mind spending some Robux, purchase the Double Server's Luck upgrade from the Shop on the top of the screen. This increases the luck of catching rare items, including Resin, by two times for 15 minutes. You can increase server luck eightfold by spending 399 Robux if you really want to get the object fast.
After you've fished these items from Mushgrove Swamp, head back to the Grand Reef where the Mysterious Pirates ship is docked. Talk to the Bubble Mermaid on the island and give her three Resins and she'll give you the Water Bubble for 25,000 coins. Water Bubble is an advanced diving gear that allows you to stay underwater as long as you want, unlike regular gear which has a limited oxygen carrying capacity.
For more on Fisch, check out How to get the Champions Rod in Fisch (Atlantis Update) and All 59 Fishes in Atlantis (100% Bestiary) – Fisch on Pro Game Guides.
