Largest 3D-printed ceramic reef
Summer Island MARS reef installation
2.41 x 2.29 x 1.90 m dimension(s)
Maldives ()

The largest 3D-printed reef structure built from ceramic is the MARS (modular artificial reef structure) installation located off Summer Island in the Maldives, which was added to an existing coral nursery in July 2018. Designed by Alex Goad, the artificial reef was assembled and installed by Goad and his team from Reef Design Lab (Australia). The final pyramid-like, latticed design comprises 36 modules and 12 half modules and has dimensions of 2.41 x 2.29 m (7 ft 11 in x 7 ft 6 in) for the base - giving it a footprint of around 5.5 m2 (59.2 sq ft) - and stands 1.90 m (6 ft 3 in) tall.

Each MARS module is a hollow shell 3D printed from ceramic using the slip casting process; the modules have a naturalistic lattice structure and uneven, pitted surface, emulating natural reef environments. Once on location, the moulds are filled with pH-neutral marine concrete to weigh them down, before then being assembled by divers in situ on the seafloor and secured together with steel screws. The Summer Island MARS reef is located around 7 m (23 ft) below the surface on a coral farm used to propagate coral which can be relocated back to natural reefs to replace damaged coral.

As coral reefs around the world increasingly come under threat from rising temperatures and other human-caused damage, there have been numerous attempts to build artificial reefs in the last few decades, with varying degrees of success. While the intention behind such projects has always been worthy, in recent years, there is a growing acknowledgement that the manufacturing process or materials used to create such artificial habitats must be sustainable and environmentally sound, as to ultimately avoid ending up causing more harm than good.

The first 3D-printed reef comprised two sections made from a pH-neutral sandstone-like material, each weighing 500 kg (1,100 lb), installed off Bahrain in 2012. They were created by Reef Arabia, a consortium consisting of Sustainable Oceans International, DShape and 3D software specialist James Gardiner (Australia).

Other materials used to create artificial reefs have included concrete, sand, metal, glass and even entire ships, intentionally scuttled to serve as a substrate to encourage coral growth. More recently, in August 2020, terracotta was used by a team of marine scientists and architects from the University of Hong Kong to 3D print hexagonal “reef tiles”, which were then installed on the seafloor of Hoi Ha Wan Bay off Hong Kong, China, where as much as 80% of the coral was devastated by a super-typhoon in 2018.