First off - you are looking for a magnetic container! It is a reach around to get at - so whilst access is wheelchair & pushchair friendly, retrieving the cache is not! Enough hints..!
Secondly - the (brief) history part!!
There have been a ferries operating between Knott End and Fleetwood since the 1830's with oar and sail power being replaced by steam in 1894.
The ferry operating now can be spotted across the river docked at Fleetwood and a series of orange dots on the Fleetwood side indicate if the ferrty is running or not!!
The ferry runs throughout the year (08:00 - 18:00) with an hourly sailing through the winter and half-hourly in the summer.
The cafe behind you marks the terminus of the defunct Garstang and Knott End Railway!