Did you know that Disney's The Rescuers actually makes for a decent adventure?
In the movie, a woman named Medusa and her accomplice, Mr. Snoops, discover a hidden cave in Devil's Bayou that was used by pirates to bury their treasure. The only entrance to the cave (that they know) is a small sinkhole. Neither of them are small enough to fit through so they kidnap Penny, a girl from an orphanage, and force her down into the cave. Despite plenty of other gems, jewelry, and valuables, all Medusa cares about is the Devil's Eye, a huge diamond.
There is a large hole in the cave, probably 4 feet across, that blocks Penny from getting to the other side where the Devil's Eye is hidden in a skull. During high tide, the seawater enters through this hole in huge gushes as the waves crash into the cave entrance far below.
This adventure could take place in the Hoach or in a cave near the Hoach (same cave system but no connections large enough for PCs to traverse). As mentioned, there is another entrance to the cave besides the sinkhole. A party of unscrupulous treasure hunters kidnap one or more children from the nearby town of Fortune and force them into the cave during low tide to seek out the treasure. This party might have tried to enter the cave from the larger, sea-level entrance and had to turn back due to the length of the route (high tide comes before they could reach the treasure and get back out), traps (if pirates buried treasure here, they might have trapped the cave), obstacles (hidden cave passages or rockfalls blocking off a route), monsters (they were just too wussy to fight their way through), or a combination of these. The sinkhole puts the child beyond most of these obstacles but not beyond all danger.
PCs would investigate the missing children, discover the sinkhole, and, if they wanted the treasure for themselves, fight their way through the obstacles from the cave entrance (or have a small PC solo the sinkhole challenges).
Edited to add: Challenges seen in the movie include a pair of alligators, a colony of bats, the waterspout in the cave, Medusa, Mr. Snoops, a skeleton (inanimate but frightening; there were multiple skeletons in the cave), and fireworks.
Helpful characters included the Swamp Folk (an overweight, motherly figure; a drunken hillbilly; a civil-war old-codger; a deacon; a hillbilly fisherman; a miner; and a dragonfly who could not talk and served as a boat's motor and a messenger).