The Humboldt Lagoons are a series of three (originally four, but one was drained and unsuccessfully farmed) lagoons on the northern California coast. They represent large bays that have been isolated from the Pacific by long barrier beaches. Occasionally a big storm and high water levels break through, but the normal condition is closed. The photo above, and the aerials, show a broad vegetated backshore on much of the barrier, but a narrower stretch at the south end. I assume this is the consequence of the breach described in detail by Nic Kraus and others in Shore and Beach (2002).
I liked the beach here - a thick band of gravel in the swash zone, but sandy above. I could have spent a lot more time exploring, but we had a lot of ground to cover (and we wanted to be in Eureka for lunch).