XT-class was the training version of the British X-class midget submarines. Six were built (XT-1 - XT-6) and two were moored on Aberlady Bay in 1946 as practise targets for aircraft gunnery and they still remain there. The dot between the wrecks is a concrete block used for mooring the subs. The link below has some excellent photographs of the remains.
Sea - Military - Submarines
Links: mysite.wanadoo-members.co.uk
By: Hinkkanen