The boat dealership lets you purchase watercraft which will then be available at any docking slip. It is located at postal 356 and looks like a white sailboat on the map .
If it is your first time browsing for watercraft, you will need to purchase a one-time boating license.
Once you purchase a boat you will receive the key just like a vehicle.
You will spawn in your boat after the purchase. To store your boat safely, you can take it to the docking slip which is nearby to the boat dealership.
You can also sell your boat at the smaller waypoint next to the docking slip.