Echolocation can do interesting things, but it cannot really go through an underground tunnel system and give you a map. This is made up for movies and TV, at least at our current level. It would actually be a lot more like what you would get by shining around a big flashlight. It locates things in an area in the dark but doesn't generally go around corners or allow the mapping of anything but what is there in the room.

Sending seismic tremors through the ground so as to find all the empty areas below would be better, but still is quite a bit short of giving you a 3D map. It really isn't that easy.

And if you used seismic tremors, you might damage the catacombs.

While there are many differences between sound and light, for our purposes here those differences do not matter too much. Trying to map extensive catacombs with sonar is a lot like trying to do it with a flashlight.

You certainly can, but it's not exactly easy.

There's a scene in Prometheus where they map a cave system that turns out is part of a space ship (as I recall).

It made me think why couldn't we do something like that with modern technology - like drones, IR cameras, echo-location style sensors, etc?

We are working on developing such things, but so far they are still science fiction.

We can ... sort of. Using conventional sensors to build a 3-D map of the space you're in isn't all that hard. The challenge is linking the map of the space you're in to the next map you'll make after you move an imprecise distance in an imprecise direction. GPS doesn't work underground, a magnetic compass can be misled by local geology, and dead reckoning accumulates errors pretty quickly.

Bear in mind this is a layman's version: I'm not a qualified sound engineer so this is based on a small amount of knowledge, not expertise. Most echolocation can only tell you where sound bounced back from in terms of a 3D space around the detector. It's basically 'line of sight'. A signal could end up bouncing off an angled wall ahead of it, around a corner, and back to the wall, then back to the detector, but all it'll really know is that the sound fired at the wall ahead of it took a long time to come back. If it's a low cost system, it'll probably just think that the angled wall is further away than it really is. If it has amazing software and incredible sensitivity, it might be able to detect the signal differences caused by hitting material, travelling, hitting material, bouncing back to the angled wall, hitting that and then returning...but it still can't 'see' around the corner - the techs analysing it will just be able to assume that the soundwave may have bounced onto something else before it returned.

Also, the strength and reliability of a returning sound echo - like radar etc - degrades with distance and contact with certain materials (it's one of the principles used in 'anechoic tiles' etc used to try to help submarines be more stealthy and minimise sonar detection in the seas). Probably your best odds for getting echo-location mapping of the catacombs would be via autonomous drones that can fly their way through the system while somehow carrying the necessary broadcast/receivers...but there are problems with that too: -

• Current drones use large, noisy rotors which doesn't make them a great choice for sonic sending/receiving.
• They're not able to fly for long and that gets worse if they carry heavy equipment. The equipment needed for this would probably be mounted to 6 axes (front, left, back, right, up, down) and too heavy
• Unless you're willing to risk having the drone save all the data and trust that it'll return intact, you'd need a way to broadcast it back. That's going to be a really big problem in the catacombs, where signals won't travel well.
• GPS won't be any use for navigation or updating the drones' positional data, so you'll need drones that can record every variation of their movement to give you accurate mapping upon their return. More electronics = more weight and power demands.
• And yes, the mapping drones in Prometheus are awesome ;) Lol