I think the way to approach a tidal sump is to go in on a falling tide and, if it opens well before low tide, then you have a safe hour or two to explore.
Poses the Jrat awards team a problem as it is an outlier but currently would be a contender.
Perhaps it is time for dedicated diggers of Portland to cast off the shackles of CSCC tyranny and strike out in a new shining era under PFPC (People's Front of Judea Portland Caving)...
There is a tidal cave at Arromanches-les-Bains in Normandy. It sinks at the foot of a small ridge behind Arromanches and resurges through cobles on a slip way in the beach.At the sink there is a notice and a brief description of the cave. It is only access via a pot on the ridge. But no information is given of the location.
Bad Behavior has blocked 1198 access attempts in the last 7 days.