Why Are There Wrecks Of Mini Subs In Aberlady Bay, East Lothian?

They were towed there by the British Navy in 1946 and used as target practice for a few years, before being left to rot.

Lot more detail here, including pictures and history.

They were training versions of World War II Midget subs (XT Craft), presumably having outlived their usefulness once the war ended and new, better, bigger, faster, etc. Subs were planned.   And in those days recycling wasn't considered so valuable, so....  The Navy managed to get some use out of them, at least.

They are quite close to the low tide water mark.  Important to remember if you ever want to venture out to explore them.  The tide starts coming in very fast.

There are also some wrecks of fishing vessels in the bay, but usually further out so not a realistic prospect to try to reach them.