An underwater rapid repair material for marine steel structure comprises: 20 to 50 parts by weight of an alkali activation material, 3 to 12 parts by weight of a fast hardening waterborne polymer curing agent, 2 to 8 parts by weight of a fast hardening waterborne polymer precursor, 30 to 100 parts by weight of an aggregate, 1 to 5 parts by weight of an activator and 3 to 20 parts by weight of a water. The underwater rapid repair material provided by the present invention is not dispersed and segregated in water, with an initial setting time as low as 0.5 hours and a final setting time as low as 1.1 hours, after pouring 3 hours, the compressive strength and flexural strength can reach about 60 MPa and 10 MPa respectively, and has high bonding strength to steel and is not easy to fall off after solidification.

A restoration cap unit for construction of eco-friendly structures in a body of water is provided, which is constructed from materials including a primarily calcium carbonate material; and a cement that is capable of holding the primarily calcium carbonate material, wherein the restoration cap unit has a first side and a second side which are attached at an edge to form a tent shaped structure, such that the restoration cap unit is configured to be placed on top of an existing restoration assembly to extend the height of the restoration assembly.

An application and a composition of bioremediation agents and cremated remains forming underwater sanctuaries and structures by coral reefs comprising a homogenous mixture of calcium compounds, clay, cement, earthworm enzymes, and human/animal ashes. The composition will benefit nearby reefs with added calcium for rehabilitating reefs and earthworm enzymes with detoxifying properties. The underwater sanctuaries and structures will provide habitats for wildlife.