If you clicked this article thinking it would be an introduction to underwater demolition, I hate to disappoint you. For that, you can get Navy SEAL training (and if you do, good for you, I hear it’s really hard). Instead, we’ll dive into the subject of sinking ships and other vessels with the purpose of creating an artificial reef.
Advantages to artificial reefs
Many underwater areas around the world do not lend themselves particularly well to marine life. They are quite simply too desolate, consisting of nothing more than a sandy ocean floor, which beachgoers enjoy because there are no rocks and little seaweed. But marine life prefers the opposite. A sandy ocean floor doesn’t support an ecosystem very well. An ecosystem starts (typically) with plants; in the ocean, this is usually in the form of algae. These organisms need something to affix themselves to, and on natural reefs, this would be a rock formation. But they can stick equally well to a submerged ship. Once the plants are there, the fish and other marine animals that feed off of them arrive, and with them the predators, and so on and so forth. In this way, an artificial reef can boost the marine life population in an area, and in surrounding areas.
Artificial reefs are also beneficial to the local economy, partly due to better fishing trade (if allowed), but also because divers love to dive on anything but a flat, sandy ocean floor. Sink an interesting vessel, such as a war ship, and they tend to flock there, bringing in tourist money.
Disadvantages to artificial reefs
Any time you introduce a foreign object into an ecosystem, there are always potential disadvantages. One of these is of course that wherever it is introduced must not disrupt currents or the migratory movements of the area’s inhabitants. Second, any toxins in the foreign object, such as oils or other chemicals, can pose a threat to marine life. This has been a challenge for the US program for creating artificial reefs, leading to a modification of the 1975 act that started the program, which now means that vessels built before 1985 cannot be used for reefs, as these often contain PCB. These considerations have meant that some nations have been reluctant to give dispensation to sink vessels for reefs.
Creating an artificial reef
Due to the disadvantages, it’s important that before any ship or other vessel is sunk, it’s handled very thoroughly. First and foremost, all fuels, oils and other chemicals must be cleansed away and removed in a responsible way — not by simply washing them down the drain or out to sea. Then, any harmful substances, such as asbestos and PCB, must be identified and removed. Because these materials are usually used as flame-retardants and insulation, they are often placed inside walls and between floors, making it harder to find and dispose of them. Wires, particularly copper, also often need to be removed.
Once the environmental threats are removed, the vessel must be made safe for future divers, in particular if the reef/wreck is large enough for divers to penetrate the structure and swim around inside. This often includes removing large parts of the superstructure, as this can collapse on itself as salt water weakens the structure over time. Then, any potentially dangerous areas need to be sealed off, and any doors and other openings that can accidentally close, trapping a diver, must be removed altogether or welded shut, so no diver can come through them. In some instances, guidelines are installed, to help guide dives through the wreck and outside again.
In some instances, wrecks may have features that are best kept in place, but that must be secured to prevent divers from trying to remove them. This includes ships’ bells, or deck guns, as in the case of the P29 wreck in Malta.
All in all, it is a costly affair, which is why many authorities around the world involve volunteer workers from local dive clubs to help with some of the work. But if done right, artificial reefs can be a huge win, both for the environment and for divers.