Overgrown River

Throughout the Everglade you are destined to traverse many rivers and if lucky enough you may find a bridge there waiting to help you across.

Those bridges have been here for longer than any life of the swamp, engraved with markings no one can comprehend. At the end of the rivers one may find there to be a tiny entrace or exit to a nearby cave system, although the gap seems to small to crawl through or is it...