Various embodiments of underwater wellhead closure systems are described that include a template having first and second anchoring ports and that is configured to be secured to a floor of a body of water. A suction pile having a cylindrical body with a head portion and an open bottom can be coupled to the first anchoring port, such that the suction pile can provide additional hold down force to the template. The system can also include a suction cap coupled to the second anchoring port, and having a cylindrical body with an open bottom and a head portion having at least one suction pump.