Why scuttling a warship is an environmental gamble

Why would environmental groups oppose scuttling a cleaned warship to create an artificial reef?

Because the reef benefit is uncertain before sinking, while a contaminated or badly placed wreck can cause lasting damage.

A cleaned hull may become a useful artificial reef, but the outcome cannot be guaranteed before the ship goes down. Residual contaminants, preparation mistakes, or an unsuitable resting position can damage the marine environment instead of improving it. Environmental objections therefore concern uncertain consequences rather than automatic hostility to naval heritage. The watch point explains why success after scuttling does not make the original risk assessment unreasonable.