Littleton Lake (AKA pit) has been used by local clubs for training for years.
The viz can get quite reasonable (3M) when (like most freshwater) it hasn't rained recently (and thus carried mulch into the water).
For training it is fantastic year round and many land logged London divers keep their hands in here during the winter. There's a couple of cars and a platform (sunk by Hounslow BSAC 1988-ish).
There are a lot of fishermen and so a lot of fish here. I personally have seen a pike longer than me (5'5') my buddy measured me beside it. I have also seen 6 huge mirror carp in procession. On a good day (late summer) the water's warm and it is a pleasant dive. November is excellent night dive time (especially for divers afraid of the dark as nothing with attack you here!).
It's harder to get in to the little bay now. There used to be so many cars and divers walking kitted up across the blind curve on the busy road that someone closed off the entry point and stopped the parking. Check out the sailing club for the latest info.
Facts about Littleton Lake

• It is in United Kingdom
• The typical depth is 0-10 Metres 0-30 Feet.
• The typical visibility is 0-3 Metres 0-10 Feet.