Just had to try this cache (as well as GC1PRBB) so went out at low tide tonight. Went with my Wife's Uncle's Wife. Long walk to the island. We headed out about 40 minutes before low tide and got back about 30 minutes after. Amazing how fast the tide comes back at times, when coming back we looked back to where we just walked over and what was sand was now water after only a minute.
Very nice treasure chest, I brought back a coin for my son and left a feather behind.