Why an electromagnetic whirlpool? What is that from? Sounds planar. Might there be exploration options and challenges outside the Material Plane for higher level characters? What else the DMG have? Let's see...
- DMG is filled with all kinds of planar hazards and complications starting on pgs.45-67. Planar portals, Astral Plane challenges like finding Color Pools and surviving Psychic Wind; Ether Cyclones on the Etheral Plane; Feywild situations like like Fey Crossings, Memory Loss, Time Warp; Shadowfell Despair; then there are hazards in a bunch of the Outer Planes.
These are all things that can be used for exploration challenges at higher level. That is important because the game also says that these are the kinds of places that high level heroes may be exploring. Sure, there can be more. But the DMG is a starting point. That said, with their stated desire to make higher level encouters more challenging maybe the new 2024 DMG will add more ideas.
What it comes down to is that you don't need a detailed subsystem for one class in one book. The designers just need to add options that are appropriate for the adventures and regions in question. Other books can have local exploration opportunities appropriate for those regions. For example:
- Out of the Abyss has Underdark travel, exploration, and foraging rules starting on p.18.
- Tomb of Annihilation has local exploration challenges starting on p.38.
- Ghosts of Saltmarsh has Environmental stuff starting on p.202. Whirlpools are on p.206, by the way.
And finally, they have already admitted that the DMG got the least amount of attention during D&D Next. Hopefully they are able to do better in the 2024 book. Cheers!