They are very useful for increasing your fishing level without actually having to fish. Fish caught with Crab Pots (Lobsters, crabs, etc.) also count towards the Mother Catch [[Achievements|Achievement]].
Crab pots can be [[Crafting|crafted]], or purchased for {{price|1500}} at [[Fish Shop|Willy's Fish Shop]] once you've reached [[Skills#Fishing|fishing skill]] level 3. Three Crab Pots are the reward for completing the {{Bundle|Crab||y}}.