The structure and composition of the intertidal zonation pattern on Solomon Islands exposed shores has been studied with reference to a series of transects on the south and east coasts of Banika Island, Russell Group. The generalized zonation pattern is as follows: (1) Maritime zone with halophytes such as Ipomea pes-caprae, Scaevola and Pemphis. (2) Littoral fringe characterized by littorinids and neritids. (3) Eulittoral zone, divided into: (a) upper eulittoral, generally with limpets and neritids, but, except in shaded conditions, bare of a well-formed balanoid barnacle zone; (b) middle eulittoral, carrying attached bivalves and the barnacle Tetraclita in shade, but under strong insolation marked by an often white-bleached cover of Neogoniolithon (there is an extensive cryptofauna that has retreated below the sun-warmed surface); (c) lower eulittoral, with the beginning of pink and brown red algal turfs, and extensively scoured by urchins. (4) Sublittoral fringe marked by a profusion of coral species, briefly exposed to the atmosphere under strong wave attack and also by a proliferant development of green algae (Caulerpa, Chlorodesmis, Dictyosphaeria, Valonia, Chaetomorpha, etc.), of the brown algae Turbinaria and Sargussum and numerous red algae, especially the calcareous Jania and Amphiroa, and Cheilosporum species as well as massive encrusting calcareous Rhodophyceae. The variety of corals increases with descent to (5) Sublittoral zone, only briefly exposed at suck-back of waves. Except in sub-maximal exposure, the corals are still outstripped in ecological importance and biomass by the encrusting and cementing red algae, especially a clathrate Porolithon. Variation of intertidal topography, based upon geomorphological features of the coral limestone, was responsible for important modifications of zoning pattern. The distinctive habitat types include narrow benches with maximal wave attack and, sloping shore profiles, with freely mounting surge, as well as beaches of mobile boulders. The predominant intertidal formation is that of a bench dissected by an inner and outer moat. To the seaward of the outer moat lies a surf crest, with lavish development of calcareous and other algae. The outer moat, often breached by surge runs to the open sea, is rich in faviid corals. The inner moat, in greater shelter, has Montipora digitata, as well as the grass Thalassia hemprichii. Detailed comparative studies were made at Titiana Point, Gizo Island; at the Spit Reef, Wickham Anchorage; Wickham Island; and at Kopiu and Waimai, South Guadalcanal. The distribution of the Mollusca, especially the Gastropoda forms a clear-cut pattern, widely applicable in the Solomons Islands. The upper shore has a predominance of littorines, nerites and patellid limpets. The middle eulittoral supports a large series of carnivorous prosobranchs, principally subsisting upon the rock-cryptofauna (sipunculids, Lithophaga, Lithotrya, and euniciid and nereid polychaete worms) in addition to a nestling fauna occupying vacated galleries and burrows. Where moats or shallow pools provide continuously immersed stretches between tides, a different, and much enriched, zoning pattern is evident. In the eulittoral zone, zoanthids are typical, as well as wide areas of Padina and - in the sublittoral fringe - Sargassum and Turbinaria, and corals, especially Acropora, Porites and faviid species. With the transition from maximal wave exposure towards increased shelter, the intertidal zonation is altered by (i) vertical and (ii) horizontal effects. For vertical effects, less marked than on corresponding temperate shores, there is still a marked elevation of the successive zones, to occupy areas well above the nominal tide limits. With decrease of wave exposure, five distinctive types of intertidal pattern have been recognized. The Solomon Islands intertidal pattern harmonizes well with those previously studied at the Seychelles, and shows broad general affinities with the sequence of zoning in Hawaii and with the subtropical Florida shore.