proposal: procgen underground rivers suggesting Svy as source of salt marsh

[jojoknob]

In the pattern of the waterlogged tunnel increase the chance of an underground river spawning under the hills and desert canyons separating the jungle and the salt marsh. Potential of river system to connect cave region around Joppa to cave region around Kyakukya for an alternate route to Kyakukya amenable to characters with tibular hydrojets, swimming skill, and/or albino. Potential to connect Red Rocks and Rusted archway as nodes suggestive of an ancient river system sourcing from Qud and sinking into Moghra'yi. Balance importance of overworld travel and its numerous fast travel speed buffs with the role play potential for underground-oriented builds to be invited to explore lateral/horizontal traversal of the underground in similar fashion to how the spiral borer invites vertical traversal.