The main reason I find this area so interesting is that everything is accesable by train. Ware-Liverpool Street on East Anglia gives you full access to the upper Lea valley. Central line to bank gives you access to the dockland where you can access East India Dock and Bow Creek Nature Park. Alternatively, change onto the District at Mile end and travel on the District Line to Bromley-by-bow, where you can acces Bow creek. Then re-board, change to the C2C at Barking, and you have Rainham Marshes and all of the other Thames marshes in front of you.
WATCH THIS SPACE!!