My Dad bought his house backing onto the lake because of the uninterrupted view right across the island to Hadleigh Castle- so he was a bit annoyed when the Lawrence Housing Estate was built (he had been told the ground was too marshy ever to be built on).
However, during its construction (around the mid 1970’s- it was finished by ’76), large blocks of polystyrene foam ended up in the lake- and they made great rafts for kids!
I got one, and shaped it (with an old breadknife) so it had proper bows, made an anchor, and took to the lake- spending many happy (and dirty) days rafting along it. Several other children did the same, so there was a small fleet of these polystyrene rafts.
I trod down a crooked path through the reeds (so it was difficult to spot while walking by) and a patch of reeds near the clear channel, so I had my own secret harbour.
Thankfully, nobody ever fell into the ‘quick mud’ of the lake!