I noticed this one a decade ago but never seemed to have the time to attempt the almost 6-mile round trip walk from the parking area to the cache and back. Besides, the last "DNF - Needs Maintenance" log from an experienced cacher wasn't encouraging, but today I had the time, the weather was fair and the worst I could do was log a DNF and "Archive" log if the trek was impossible.
From the satellite view, the bridge and trail had been washed out some time back on the final approach and would have to be done on the riverbank. The tide was outgoing, nearing a spring low, so I had some hope of making it to the island with dry feet. Besides, although the last finds had been using watercraft, I've lived on the coast most of my life and can distinguish firm sand from pluff mud from afar.
About a quarter mile from the final, the rail bed was badly washed out and finally disappeared so I walked down to the riverbank and was pleasantly surprised that it was relatively firm sand with occasional patches of oysters. Even the stretch past the missing bridge was firm with only a trickle of water. (I attempted to return to the trail just beyond the remains of observation deck, but decided it would be easier to stay on the riverbank until close to the island.)
Once I was about 150' from the final, I crossed the marsh onto the island and was blown away by the really cool and funky area. The decor indicated that recent visitors were not worried about drug tests. (I had done a cache out here about 20 years ago when it was still easily accessible and was surprised that the trash cans and picnic tables were still there, despite many storms in the interim.)
Lots of potential hiding places, but since it was listed as a "LARGE" container, I thought I was looking for a 5-gallon bucket, so it took me a while to spot a standard ammo box. All of the swag was in good condition and the log was pristine.
On the way back, I stayed on the riverbank for about a half mile and returned to the trail when the marsh started to widen and look muddy.
If you're looking for a fun challenge, this one's for you!