This paper gives a detailed description of the Wheeler North Reef at San Clemente, CA. The reef was designed to grow and sustain giant kelp and the associated ecological community. This reef is the largest human-made reef constructed in the United States (70.60 ha, or 174.4 acres). It was constructed in two phases. The Phase 1 Experimental Reef, with a 9.06 ha (22.4 acres) seafloor footprint, was built between 18 August 1999 and 29 September 1999 (35 construction days). The Phase 1 reef consists of 56 modules, sized at 40 m by 40 m, with various hard substrate coverage densities (low, medium, high). The experimental reef was monitored from 1999 to 2005 to assess its performance. The Phase 2 design was based on the results of the monitoring program. Phase 2 construction began on 9 June 2008 and was completed on 11 September 2008 (73 construction days) adding 61.53 ha (152 acres) of reef substrate. The Phase 2 reef consists of 17 polygons varying in area between 0.56 ha (1.4 acres) and 15.74 ha (38.9 acres). The profile of the reef is a single rock layer rising no more than 0.5 m off the existing sand seafloor. This rock configuration was used because previous studies had determined that kelp in the area is most persistent on very low-profile natural outcroppings. The seafloor sand thickness was specified to be no more than 0.5 m with a hard sub-bottom to reduce the probability of the rocks being buried over time.