This paper is about the various options for the caisson structure for a Low Temperature Thermal Desalination plant near an island in Indian Ocean. The Caisson is circular with outer diameter of 8.15 m and inner diameter of 7.5 m. The overall height is about 10.65 m (9.1 m above seabed 1.55 m below seabed). The Caisson has to be placed 250 m into the sea from the shoreline, where 5 m water depth is available. The soil, 1.55 m below the caisson is weak coral sediments with cavities. The caisson has to resist a lateral force of about 500 T due to wave and the caisson lacks stability against sliding and overturning. Various options (i. Caisson with wind turbine, ii. Caisson with ballast, and, iii. Caisson with anchors) are considered. The comparison study based on economy, structural stability and construction methodology is presented. © 2019 Taylor & Francis Group, London.