title_body: Drones for spelunking? I do a lot of spelunking and I would like to know if anyone has some recommendation as to what type of drone would be the most useful in cave exploration with light and camera possibilities in total darkness.
  
  I am only interested in drone usage where the cave chambers are quite spacious and not for usage in narrow passageways.
upvoted_answer: If it were me, there are two different kinds of drones I would want. A tiny whoop and a cinewhoop.
  
  Tinywhoop is a loose definition of a very small drone that's about 3 inches wide with guards/ducts around its props and weighing anywhere from 20-50g. They are very durable and fly in places nothing else could. You can assemble them yourself (very easy) or buy one pre-assembled for around $100. You can add a small, powerful LED that allows some pretty fun exploration in dark and very tiny spaces without the risk of loosing a larger, more expensive piece of equipment. Example video of someone flying in their house with the lights out
  
  A cinewhoop is a larger drone, more like 6-7 inches wide and weighing 200-400g, also with ducts. Typically it's called a cinewhoop because it's about the smallest thing you would want to fly that can comfortably carry a GoPro. You could equip this with a much more powerful light and have a real blast flying around. Like tavis mentioned the DJI FPV system would be an excellent setup for caves as it has great video quality and is very resistant to signal multipathing which is a very common affliction of analog video systems like what you would install on a tiny whoop. Multipathing is likely to be a very real issue inside a cave. If you could live with the analog break up though there are few 'starlight' type analog cameras that can operate in very dark environments. However, I don't think that would be nearly as enjoyable or as useful as a 1000+ lumen flashlight strapped to a DJI equipped cinewhoop. That would be awesome. Video here of DRL pilot NURK doing a better job of explaining what a cinewhoop is.
  
  I would say your typical DJI consumer drone would not be well suited to a dark cave. Without GPS they would rely on downward-firing cameras for position hold which doesn't work in the dark. You could possibly rig up light to assist the cameras but I would guess that it still wouldn't work very well.