Surf clams, also called Coquina, are bean-sized (2 cm), colorful bivalves that make their living in one of the most challenging habitats, the surf zone. They are filter feeders, extending their siphons into the water as it washes over them. As the wave pulls back out, they are often exposed at the surface and have to quickly put their muscular foot down to scoot back beneath the sand.
I used a Sanyo Xacti E1 for this field test. The little camera is immersible to 5 meters. I did not need to send it that far down to video these little guys, as they are in the wash zone of the beach. Video was edited in iMovie and scored in Garageband. Note, this is not time-lapse footage. The clams really do dig that fast.