The storage buildings are the Boathouse and the Silo. The Silo holds crops and fruits. The Boathouse holds crafted Goods and everything else. As you increase your crops and crafting, you may run out of room and need to expand the amount of storage space. You do this by upgrading the storage buildings.
Each storage building requires storage parts in order to upgrade them.
The Silo requires:
pulleys
nails
rope
The Boathouse requires:
planks
anchors
life rings
Earn these storage parts by:
sending Guides and Guests to the island landmarks (such as the Coral Reef, Hot Spring, Merchant Shipwreck, Smugglers Cave, etc.)
opening Treasure Chests at the Sunken Temple
Quick ways to deal with running out of storage space:
upgrade a storage building using Gems
craft Goods to use up stored ingredients
- sell crops or Goods at the Trade Boat or Order Board