Mangrove plays the importance of roles for the small island sustainability both physically and ecologically. In the high-risk Pacific Ocean's islands, Papuan small islands face typhoon, earthquake, high wave, and tsunami effect. Mangrove could be optimized as the natural structure to reduce the risks. Various explorations on North Part of Papua were compiled to figure out mangrove structure and potential. The study was conducted at 200 10mx10m-quadratic-plots scattered on 14 small islands in six regencies in the northern archipelago. Research objectives were to investigate mangrove community structure on each island i.e. canopy coverage, density, and morphological size; and to analyze the correlation among those parameters. The general result found that mangrove condition in all island was in pristine condition, high individual size with low anthropogenic threats. In detail, they were covered by a medium and dense canopy from 61.32±3.04% in Pasi island to 93.88±0.14% in Meos Mangguandi. Substrate composition significantly influenced the level of canopy coverage and controlled the MDS ordination of species composition. Sonneratia alba tended to be dominant in rocky sand in Pasi, Owi, Padaidori, and Wundi, while Ceriops and Rhizophora were mostly occupied the muddy sand, or Bruguiera gymnorrhiza has the highest domination in sandy mud substrate in Auki, Pai and Meos. The canopy coverage had a significant correlation only with total density but none with the others. Height of tree (up to 21.2 m) was found highly related to the diameter size (max: 124 cm).