To find this cache you will need to plan your visit at low tide (below 1.0m) as for most of the day the cache will be submerged. The walk from the closest parking is 2km away so allow some time for your attempt.
As I'm not sure how the tide will affect the cache I have included the photo below to show you its current location, attached to a boulder and pressed up to a fallen log (one of several in the area) 865m from the shoreline at the end of Batley Parade.
Inside the cache you will find a log inside a bison tube, a pencil and some foreign coins. Hopefully the contents will be dry.
Congratulations to Frullet for being the FTF.