After completing Hull Breach and Blood Tide, Teddy Wright of Far Harbor will approach you and tell you about the “Captain’s Dance”. After the conversation, the quest Living on the Edge will be completed and this quest will start.
Head to the causeway east of Rayburn Point. Head to the marked spot and drop any kind of raw meat to call in some mirelurks. Kill them all then drop more meat in the water. Destroy the second wave of mirelurks until finally the mirelurk queen appears. Defeat it and head back to Far Harbor to report your victory to Teddy.
After his speech, talk to him to complete the quest and receive your reward, including The Captain’s Hat and The Captain's Feast. The next quest will be activated automatically.