The submarine will be your main and only vehicle in the underwater caves and to travel to its sub-locations. It does play an important role, and fortunately, there's nothing complicated to get it.

With our detailed guide below, you will learn how to construct the Submarine at Roslit Bay. The guide will also help you upgrade the Submarine with the Heat, Ice, and Deep upgrades in Fisch.

Here is everything you need to know about the Submarine Worker NPC in Blox Fruits, including how to find and use him.