The Lighthouse Cove is a stationary building on the Lighthouse Cove farm, which takes up 25x17 (425) squares or 6¼x4¼ (26.5625) plots. It can be harvested for clam bushels, seafood bushels and lobster bushels. It can be upgraded. It cannot be moved, sold or deleted.
Depending on the Stage you want to upgrade to you need several amounts of these materials. Stage 1 needs 3 of each, stage 2 needs 5 of each, stage 3 needs 10 of each, stage 4 needs 15 of each, stage 5 needs 20 of each, stage 6 needs 25 of each, stage 7 needs 30 of each, stage 8 needs 40 of each, stage 9 needs 50 of each and stage 10 needs 60 of each. The last Level so far is Level 10.
It can be harvested daily, if you are at stage 1 it will only give clam bushels, with upgrading you will then qualify to get seafood bushels and later lobster bushels. However you will get one of the bushels you qualified for randomly.