Land expansions unlock at Level 10.

Tap on an area where you want to expand. You'll see that expanding to that piece of land (outlined as a rectangle) requires expansion parts:

• Compasses
  
• Signet Rings
  
• Survival Kits
  

The numbers beneath the expansion parts show you many you have (the number on the left) and how many you need (the number on the right).

A green checkmark means you have enough of the expansion parts.

If you don't have enough parts, you can expand instantly by paying the Gem price shown on the Expand Now! button.

Find the Compass, Signet Ring, and Survival Kit by opening Treasure Chests at the Sunken Temple.

Expansions will have more debris to clear for useful rewards as well as Treasure Chests to open for even better rewards.