Concrete has had extensive use as construction material for seawalls, jetties, groins, breakwaters, bulkheads, and other structures exposed to sea water. The performance record has generally been good. Cases of comparatively rapid deterioration have usually resulted from failure to consider and compensate of the conditions to which marine concrete is exposed. The following practices are recommended to produce marine concrete of excellent durability. One, proper mix proportions using the optimum cement content will yield a dense, impervious and relatively unabsorbent concrete. Two, the optimum concrete is 6 and one half to 7 and one half sacks per cubic yard and the water/cement ratio should not exceed 6 gallons per sack of cement to produce a mix that is plastic and workable. Three, reinforcing steel must have a minimum of 3 inches of concrete cover. Four, type V cement with 5 percent C3A content produces the best results. Five, non-reactive aggregates should be used. Six, an air entraining agent will reduce the danger of deterioration due to freezing and thawing. Seven, especially at the tidal zone concrete should be placed in a continuous operation. And eight, concrete should be compacted thoroughly to avoid honeycombing and to provide a dense, homogenous mass.