ABSTRACTApplication of the floating laboratory concept to hatchery culture of abalones and rock scallops was tested in 1975–76 using a mono‐hull pleasure craft. Successful experiments prompted construction of a larger vessel consisting of a deck and laboratory superstructure supported by pontoons. The facility has been in operation since early 1978, moored in a marina cove near the entrance to Mission Bay. Seawater is delivered to tanks in the laboratory when currents and tides bring offshore water into the cove. Use is made of inexpensive materials and equipment wherever possible.This paper describes the laboratory, relates successes in spawning and rearing young of the green abalone (Haliotis fulgens) and the purplehinge rock scallop (Hinnites multirugosus), and compares culture conditions and success with those at the nearby La Jolla laboratory of the National Marine Fisheries Service.