During WWII the USN / USMC had three airfields in the Marshall group: Engebi (Eniwetok Atoll), Roi-Namur (Kwajalein Atoll) and of course Majuro. On the lagoon side of Roi-Namur there are an estimated 130 aircraft that were dumped there at war's end. There are a number of R5C's and PBJ's all laying nearly side by side and of course stripped of engines. Look at the website for VMB-613 as they have photos of their PBJ's being loaded onto barges in preparation for 'final disposition'. Just to the SW of Roi (about 2 miles) there is a small island on the reef adjacent to the man-made pass going to the ocean, Just opposite that small islet there is a 'pile of carrier based aircraft' that was dumped there.
Here is the bad news you cannot go there as it is within a military area aka "The Ronald Reagen Test Site". Check out the website for the RR Test Site as there are photos of the wrecks.
Oh, yes Engebi airfield on Eniwetok Atoll. Engebi was used post WWII for nuclear testing. It may still be closed. looking at the island on earth-google it looks barren. Perhaps anything remaining there was blown to bits ...vaporized. Aircraft in the lagoon? unknown.
Out of all this there is one bit of good news. Bikini Atoll is now accessible ( i.e. SCUBA divers!) . The USS Saratoga is laying in the lagoon in very shallow water...actually you can see it from the surface as the top of the island is only 30-40 feet below. SCUBA footage I have seen shows the hangar deck FULL of carrier aircraft. I did note TBM, SB2C, F6F wasting away below. Due to time (70 years ) it appeared that the engines had broken away from their mounts.
In my time there the only intact aircraft I ever found was this severely battered Curtiss SB2C Helldiver. It was located on the former Marpi Pt. fighter strip at the north end of Saipan. It apparently is now gone. Perhaps one of the many typhoons with winds of 200+mph may have claimed it.
JohnV