Newly developed diving techniques and equipment make possible first-hand geologic observations on the inner half of the continental shelf. Using a self-contained diving apparatus such as the aqualung, a diver-scientist may descend with complete freedom of movement to water depths as great as 200 feet for periods of a few minutes or to shallower depths for as long as an hour. He can perform almost any simple mechanical operation which is possible on land including the measurement of strike and dip of rock outcrops, slope of unconsolidated sediments, and ripplemarks; the sampling of rock outcrops, sediments, and overlying waters; and the photographing of small sea-floor topographic features. Ecological problems related to geology can be studied in detail never before possib e.

An aqualung training program, instituted jointly by the Scripps Institution of Oceanography and the U. S. Navy Electronics Laboratory, prepares a scientist for underwater work after about 30 hours instruction.

Several simple geologic tools, such as an inclinometer, a sediment sampler, and a ripplemark measurer, have been developed for underwater use; watertight cases have been built for use with such instruments as compasses, stopwatches, photographic exposure meters, and cameras. Construction details and sealing techniques are discussed.