Abstract: An anchor comprising a container having: a size of at least 3 m×3 m×3 m; a plurality of chambers; at least one valve in each chamber to selectively allow and prevent fluid communication between each chamber and a surrounding environment. Exemplary embodiments also include pressure release valves provided the chambers. The pressure release valves are adapted to allow transfer of fluid between the chamber and the environment when the pressure difference between the inside and outside of the chamber exceeds a predetermined level such as 0.5 bar or 1 bar; typically to allow fluid release from the chamber when the pressure inside the chamber exceeds the pressure outside the chamber by a predetermined level. A method of deploying and manufacturing are also disclosed.