Initially experiments were tried with tyres chained together but sand movement and currents proved to be too strong and washed the tyres away or buried them. Benthic stones were used but they also suffered from tidal force and proved too expensive. This was followed by sinking of cars and monitoring the effects of sealife upon them, including a Mercedes-Benz that was towed out behind a boat prior to being sunk, driven by diver and instructor Steven Hensaw.
In 2006 the 65 ton wooden boat "True Joy" also known as “Noah’s Ark”, was sunk here. The last major addition was the remains of the MV New Flame, a mid-sized bulk carrier that foundered off Europa Point in 2007.
In 2013 a new type of reef was created by sinking of concrete blocks, with metal spikes attached. This caused a diplomatic row, as Spain claimed that these blocks were ripping fishing nets used for trawling and began discussions of whether to place a tax on visitors into Gibraltar from Spain, and close Spain's airspace for flights inbound to Gibraltar.
Greenpeace commented that; “such reefs are a very common practice. This is a diplomatic conflict over maritime sovereignty and not an environmental one.” Spain regularly “deployed hundreds of [concrete blocks] to protect its waters” from fishing trawlers.
A comparison of the biodiversity between natural and artificial habitats on the coast of Gibraltar. By Hanna-Mari Pekkarinen. Masters Thesis in Marine Ecology, Department of Marine Ecology, Gothenbury University, Sweden. Contribution nr. 210 Date: 16,01,2004
The Gibraltar Artificial Reef. Habitat Manipulation II - Dr Eric Shaw (1996). In: Jornadas de Estudio y Conservation de Flora y Fauna del Campo de Gibraltar, Almoraima 15, p. 197-204