Has anyone been through the garrison in the past year or two? There's a path that connects to the sea wall that is completely unrideable unless you are on an mtb, and even then it's a pig.
You cycle up Mess Road from Gunners Park. If you want to continue along the sea wall to East Beach you have to cross a small green at the top of Mess Road. The marked cycle lane takes you to it:
You are then greeted with this:
Unfortunately it is just mud covered with a loose layer of this:
Impossible to ride on the Moulton and extremely difficult on the Dawes. Like every other cyclist taking this route I just ride on the grass. (which is daft as the path was put in to stop people riding on the grass).