[throwmeaway33]

Well, how do you communicate with the robots? Radio waves don't penetrate water.

So say you have a robot that's autonomously floating around look at stuff and then it goes by a giant squid. There is no one to tell it "Hey! Look, a giant squid! Stop and turn your camera at that!" so it just keeps going.

Also, I have no idea how they would know where they're currently located (again, no GPS).. but I'm sure they have some solution.

One huge advantage I could see is potentially you wouldn't need to pressurize anything. Optics can easily be made to work immersed in water, electronics can be slathered in epoxy so you don't get any short circuits. Then there shouldn't be any limit to how deep the thing can go.

[epochwolf]

> Also, I have no idea how they would know where they're currently located (again, no GPS)..

US Naval Submarines have done this for a long time.

http://en.wikipedia.org/wiki/Inertial_navigation_system

[Nrsolis]

And they are good at it.

I spent some time on a submarine and navigation is one of the most critical things to the cruise.

[efnx]

What about a fully autonomous submersible that surfaces periodically to get its bearings from GPS, upload data, recharge through solar, etc... It could be programmed with a certain number of goals and priorities and follow the goal with the highest priority given some parameters.

[efnx]

Or, what about using low power radio to communicate relatively short distances to other submersibles scattered upward toward the surface, forming a mesh network that eventually has an endpoint connected to the ship or satellite?

[panacea]

Poseidon Exploratory Advanced Research Laboratory. PEARL.

A string of submersible robotic submarines linked by really long cables that are dangled into the ocean.

[DanBC]

Well, it's an autonomous robot. You only need to communicate with it on the surface. (Maybe some emergency communication feature is handy?)

You give it some kind of sensor. When it finds something bigger than 3 m at a depth of more than 500 m you start following it. I'm not saying that's easy, but we have self-driving cars and we send robots to Mars (average distance 200 million km). I'm sure we could do it, if there was interest.

[deelowe]

It's has to orient itself in 3d space somehow. Wikipedia says the best you can get with dead reckoning drifts by .6nm/hr. I'm guessing that can be useful in some cases, but it probably limits a lot.

[mailshanx]

One needs acoustic signals for underwater communication. I work with underwater modems, and we use frequencies in the 18-34 KHz range. Other modems can operate in bands from 8-50 KHz.

Autonomous underwater vehicles are an active area of research. One of the challenges involved are localization once the vehicle has dived. You cannot get GPS under water, so one way to localize yourself is by tracking your velocity/acceleration once the dive has begun. Another way is to exchange messages with your peer robots and devise a distributed location resolution scheme. See some of the work done in my lab in these areas: http://arl.nus.edu.sg/twiki/bin/view/ARL/STARFISH

[cobrausn]

This is, for the most part, a solved problem. It does require a really long cable and a person at the control panel though.

http://en.wikipedia.org/wiki/Remotely_operated_underwater_ve...