The HMS Thetis should have been one of the world’s most impressive submarines but during its diving trials in the Liverpool Bay the stricken sub sank with over one hundred crew and dignitaries onboard. There were only two survivors and when Thetis was eventually salvaged a memorial was built in the tranquil haven of Holyhead Cemetery. As a town full of maritime history, this memorial is well worth a visit, if only to be humbled by the sheer number of victims listed on the headstone.