The HMS Cassandra sank in 1918 after hitting a mine near Saaremaa, with most of its crew surviving. The wreck, discovered in 2010, contains a significant amount of oil, posing environmental risks. Experts are surveying the wreck to create a management plan with the Estonian government to prevent leaks. There are an estimated 8,500 potentially polluting wrecks globally, many from World Wars I and II, which are becoming unstable due to climate change and human activity. Project Tangaroa aims to address these issues through international collaboration and data sharing, advocating for a proactive approach to manage the risks associated with these wrecks.