Storage Boats mod adds in a boat with a chest to the game which will let you store up to 27 more stacks of items. You will be able to open the boat’s inventory by pressing the E key while sitting in the boat in the next update! Right now pressing E in the boat will open and close the chest.
A wolf on the beach.
The boat with the chest opened!
To craft the storage boat you’ll need an oak boat and a chest
For Minecraft 1.10.2