Bolton Strid, a killer creek
"Indeed while there do not seem to be any hard numbers about exactly how many people have perished in the Strid, the local legend is that no one who has dared enter the waters has ever made it out alive. The caves and naturally carved traps laying just under the surface of the photo ready river have been claiming lives for centuries."
(read more in depth at https://www.amusingplanet.com/2015/11/bolton-strid-stream-that-swallows-people.html)
What a place for a mythic underworld entrance! Consider:
- "My daughter Lady Celeste was pushed into the creek of death and vanished. I will pay her dowry* to any man brave enough to recover her body."*
* A sackful of scallions (it's a tradition, don't ask) and also a valuable silver puzzle box containing high thread-count sheets
- "My ancestor, the mad hermit of Lagrange, once stole a crown off the head of a duke and dove into the bloody brook head-first to escape, never to be seen again, except once a month at the pub for a quiet pint. We never saw the crown again."
"Strong winds and rain transform the land as rainwater fills the valleys between the dunes, creating a surreal lacework of thousands of seemingly miraculous lagoons between ribbons of sand."
This locale looks like an intriguing travel obstacle. Imagine the problems with encountering this on a hex - if you are riding by pack animal or wheeled cart, you have to make an exhausting series of river fords. If you are traveling by boat, it's completely impassible by turns, as if it was a river.
Wait, did someone say random encounters?
- Spiky tumbleweed the size of a barn ponderously rolls with the wind
- Mummified water hag sleeps in her tomb until the water comes, then spends her days farming algae and perfecting indigo dyes. Hates the color red.
- Giant enemy crab - but camouflaged under a sand dune this time
- The last of the migrating dune spiders - car sized, fast as an antelope, wants to get away from all this wretched wetness and does so with careful hops and leaps
- Crew of halfling travelers paddling light canoes - searching for the blue mummy (#2) to trade for dyes and will exchange map notes
- Several huge lush cacti surrounded by rotting corpses (mostly birds) in the middle of a lagoon - these are dune tanglers (stats as roper) and might have some loot.
'Legging' a narrowboat through a tunnel for hours"This was a time when engineless narrowboats—pulled by horses that walked along a canal’s towpaths—transported mass quantities of goods like coal, iron, and pottery along a “super highway” of inland waterways and their locks, tunnels, and aqueducts throughout Great Britain [..]"
These tunnels could be longer than 3 miles and were a major source of revenue for wealthy coal purveyors. Any problem in a commercially used canal can be assumed to have the financial interest of significant merchant traders. (Imagine the opportunity cost to businesses if a commercial highway was closed for a week)
- Traffic backed up due to distant screams of unknown provenance
- Coal barge caught on fire mid-tunnel and needs to be cleared (water breathing might help with the lack of oxygen here)
- Party asked to assist with legging a barge through, emerges in glittering outer space on the other side
- Barge is floating tavern/hotel - while moving through a tunnel, a legger breaks through into a new dungeon complex (perhaps filled with giant green ants or hobo wraiths)
- Prisoner transport vessel taken over by convicts in tunnel, hostages taken, party deputized to assist with breaking siege (perhaps by drilling through the top)
- Similar to the first idea, this classified, high-security tunnel is actually effectively a wormhole to another location behind enemy lines. This is used for furtive spy activity and economic destabilization - with the right documents, a small group could sneak through posing as a barge team and use the rapid travel to their own ends.