Movement powers: swimming

Today I want to talk about one of the under-respected superpowers an aspiring villain can have, which is amphibious adaption or super-swimming.

Swimming

Like flight, there's definite limits past which unmodified humans can't go without risking long-term injury or death. Ordinary air mixtures can't take a diver past about 250 feet, while a modified rebreather allows a distance closer to 750 feet. Navy divers have gone down as far as 2,000 feet in special suits. The only contenders for truly deep dives are specially designed submarines or mini-subs, like the Trieste (36,000 feet). By comparison, heroes like Pelagos have reported unaided dives to 20,000 feet and have probably gone deeper. I have second-hand knowledge of villains like the Deep One and Sea-czar who have reached - and sometimes casually hang out in - the Hadal zone at the lowest level of the ocean.

That's pretty incredible if you stop and think about it. That's 1000 times the pressure of the atmosphere. A mundane would be crushed flat. Even the specially designed subs meant to reach such depths will start breaking down, and it takes hours for them to get down and back again. So why do aquatic supers get a bad rap? "Earth is 70% of water", they say, which is true. The reason is that the interesting parts only happen in that other 30%, because that's where the humans are. So how do you make the most out of an affinity for water?

Lair placement

Like flying, only more so, the ability to reach depths of 1000 feet or greater basically immunizes you from conventional pursuit. Unlike flight, you have nearly infinite options for lair location - you aren't restricted to mountains, you can just dive and dive and dive until you find something you like. For this reason, aquatic villains are nearly impossible to track down. Conventional radio transmitters will cease working quickly if you were tagged for some reason, and satellite tracking isn't an option for governments or military trackers.

It's not completely awesome. Villains on teams, or who want to take a prisoner, mistress, etc. home with them, are out of luck - unless you can grant your ability to someone else, your lair is for you alone.

Caper options

Aquatic villains tend to build capers around the following:

• Piracy on the high seas. Surprisingly lucrative - unlike mundane pirates, depending on the cargo, you can just sink the ship, let the crew abandon ship, and salvage the cargo from underwater. Not always an option, of course. Sea-czar got around this by actually flipping ships, which left the cargo hold high and dry but obviously screwed the crew up but good.
• Use of waterways as an approach or getaway tactic. Villains have operated everywhere from Venice to the Mississippi river by sneaking up on their target, doing the job, then swimming away.
• Storage of valuables in unexpected places. Watch the 2003 "Italian Job" for some ideas here - the thieves drop a safe into the canals, then send a decoy speedboat to lure the cops away while two guys crack the safe underwater. Similarly, the "Kraken Skulls" villain duo would steal fully loaded tractor-trailers. Skulls would drive the truck off a dock into the water, and Kraken would retrieve its contents.
• Use of water as an area denial tactic. This isn't something you can do in every time or place, of course. The Deep One was fond of blowing dams, then swimming through the drowned areas and looting whatever he could.

Some specific considerations for underwater capers:

• If you are driving vehicles off docks and the like, remember that the weight of the engine will tend to pull a car down nose first, and probably flip it. Big rigs do the reverse, since most of the weight is in the trailer.
• When working with a team, remember that you probably can't just communicate freely with them. Some teams are accustomed to a secure radio hookup. In such cases, the underwater members can buy specialized wireless transceivers and similar gear from companies like Ocean Technology Systems. OTS also sells ComRope for wired communication, if you are worried about having your comms sniffed.
• Dive watches (ISO 6425 compliant) are rated for a specific depth, and they're getting better. If you need to schedule your capers, or otherwise just keep track of the time, make sure it's clearly marked as a diver's watch.
• The magic distance for bullet penetration is about 8 feet. Get deeper than this, and people shooting at you from the surface are out of luck. If they're using assault rifles or something, it's more like 10 feet. By comparison, the canals in Venice are fairly shallow - 6 feet or less. The grand canal is closer to 15, but it's still a tight fit.

That's it for aquatic operations! Remember that there are no stupid or useless powers, only stupid or useless supers.

Late Addendum

"Pacific Pirate" writes in to talk about the subject of sonar detection. I'll let her message speak for itself:

Mr. Big, you talked about detection for flyers, but not for us aquatic types. The thing every super-swimmer has to know about once they wade out of the kiddie pool and into blue water is thermoclines. 

Thermoclines are layers in the water that reflect sonar. They're created by temperature differential. They're found at specific depths - you can feel one as you swim through it. They're crucial for us because of the use of hydrophones and sonar is becoming more prevalent. Modern hydrophones are sensitive enough to pick up a typical super-swimmer within a few miles. That may seem like a lot, but it's not when you're diving. Still, it's a problem. Passing through a thermocline hides you from these instruments. 

Understanding sonar in general is probably useful too, so here's some additional information.
Sonar is being used to repair trans-oceanic cables, find oil deposits for offshore drilling, look for wrecks, and gather geological data for volcano monitoring. It's also being used to find our underwater bases, and track us. Side-scan sonar will pick up protrusions from the sea bed immediately. If you plan to build an underwater base, find a cave system, or burrow into the surface if you can. Building a structure up from the sea bed will be spotted. This is only an issue if someone has scanned the area before and can do a comparison, of course. When in doubt, do some research and see if you can find evidence of prior scans. 

Thanks for the shout-out, and good luck with your guide!