Existing protective structures at Waikiki Beach consist of 
sea walls, (Figure 3) groins (Figure 5) and a short offshore 
breakwater. (Figure 7). The sea walls, of various types, ex- 
tend along most of the length of the beach. The groins are 
short and, although of too light design to withstand heavy wave 
action, have suffered little damage over periods varying up to 
ten years. 
The offshore breakwater is 700 feet long, 250 feet offshore, 
and cellular in type. It was constructed in 1938 of interlocking 
precast concrete slabs forming cribs which were filled with rock 
fragments and boulders to the top elevation of mean lower low 
water. At mean higher high water the breakwater is submerged 
about 2 feet. The area landward of the breakwater was cleared of 
coral patches by a dragline excavator and 7,000 cubic yards of 
sand obtained .from a nearby municipally-owned beach park was 
placed artificially on the beach. As the project neared com- 
pletion, it was apparent that the newly deposited sand tended to 
move northwesterly, and shore returns were constructed at each 
end of the breakwater to retain the sand in the inclosed area. 
Figure 6 shows the condition of the beach opposite the site 
of the offshore breakwater prior to its construction and artifi- 
cial placement of sand fill. Figure 7 shows this improvement 
FIGURE 5. TYPICAL GROIN 
