This is a nice walk for a warm still day as there is no shelter. It has to be done at low tide too. I have rated it difficult because it might be dangerous if you get your tide information wrong. The actual sand and mud terrain is easy if the tide is out. You will need to wade across some creeks. The minimum altitude error might have been caused by dropping the GPS into a creek. This would cause a significant pressure increase / altitude drop. The GPS seems to have survived the dunking.