Submarines can act as great locations for adventures, as ‘Cold War’ illustrated. Tight confines, isolated, surrounded by a hostile element that forces the crew to be entirely reliant on technology. It doesn’t take much for things to go wrong very quickly.
There are obvious parallels between spaceships and submarines allowing science fiction stories to be easily adapted to feature submarines and vise versa. It is a perfect way to balance a historical set adventure yet explore science fiction ideas of man vs machine and man vs nature.
Submarines bring with them inbuilt tension. The majority of submarines are used by the military. ‘Cold War’ explored a tense period between the East and the West, where both sides were poised on the edge of a nuclear war but submarines were used during both World Wars.
Ships were hunted by submarines, who could sink them with well placed torpedoes. Once their presence was detected the tables could be turned on the submarines, forcing them to flee from depth charges or escape other submarines.
In the 21st century submarines are more likely to be carrying nuclear weapons, making the stakes even higher. Recent tragedies at sea have shown that they are no less vulnerable to the dangers of the ocean.
Any adventure involving submarines should have a healthy dose of suspense. The submarines position of power is precarious. Tip their hand too soon and they’ll be running for their lives.
The close confines within the submarine allows for some heated relationship between NPCs. When creating the supporting cast it can be useful to decide who is loyal to the captain, who is having doubts about their cause, who has only recently begun their military career and who wants to retire while they are still alive? All of which can become useful if the crew should have to choose alliances during the course of the adventure.
The nationality of the crew can affect how they react to the PCs. The TARDIS can remove or reduce this problem, by allowing them to speak the language of the submarine crew but that doesn’t eliminate them being accused of being spies or stowaways.
Indeed, a submarine is a very difficult place for PCs to explain their presence to the crew. There is little chance that any of the crew will believe that they just haven’t noticed the PCs until now and fewer opportunities for them to have boarded legitimately.
It can create an ethical dilemma for the PCs if the goals of the submarine crew threaten those that the PC is loyal to. A British PC who finds himself on a German submarine during World War 2 might try to stop them sinking a British ship, even if it is a part of history.
Even without the presence of an alien being a submarine offers its own dangers. Technological failure can trap a vessel at the bottom of the ocean, with the air and power running out. If it begins taking on water it can be only a matter of time before everyone drowns, that is if the submarine isn’t crushed by external pressure.
The tight confines of the submarine are the worst place for a hostile life form to be on the loose. An Ice Warrior is just one example of the kind of savage alien being that a submarine might accidentally bring on board.
A shape changing alien could make a submarine quickly start to question each others identity and double guess every order they are given. Paranoia can seize the crew, making the situation much worse.
We still know very little about the life that exists within the oceans, giving rise the possibility that the PCs might discover something incredibly strange yet terrestrial in origin.
The submarine may discover the danger itself, discovering mysterious ancient ruins or an alien craft submerged beneath the waves. The submarine crews natural curiosity may lead them to awaken something that was best left undisturbed.
When things go wrong the PCs can be key to guiding the crew in the right direction. As outsiders they are free of the power struggles and alliances that have already formed. They are impartial observers who can attempt to persuade others to follow their advice.
The stakes can be as low as saving the lives of the crew to saving the whole world. With the PCs trapped on the submarine they know that everything depends on them. There can be no outside agency that can come to the rescue.
A submarine centred campaign is entirely possible. With the number of aquatic alien threats previously encountered it makes sense for UNIT to have at least one submarine dedicated to protecting the oceans.
Such a campaign could focus on repelling the efforts of the Sea Devils, Zygons and Rutans from building a powerbase beneath the sea. The action does not need to be restricted to just the submarine, since aquatic alien races will often surface to strike at mining rigs or raid coastal towns.
The existence of multiple Atlantis allows UNIT to discover other mystical cities. What might they reveal about Earth’s past? What treasures might they hold? The PCs would need to answer these questions before their enemies can.
If you want a more science fiction feel there is no reason that submarines wouldn’t be used on alien planets. Humanity might still use submarines to defend the seas on other worlds and discover their secrets.
The movie ‘Hunt For Red October’ can serve as further inspiration for Cold War submarine action, while ‘Crimson Tide’ explores the clash between commanding officers over an order to launch a nuclear missile.
The short story ‘The Temple’, by HP Lovecraft, details a WWI German u-boat coming under the influence of an arcane artefact.
The Twilight Zone episode ‘The Thirty-Fathom Grave’ uses a sunken submarine as a source of mystery, as despite lying at the bottom of the ocean for 21 years banging can be heard from within.
In the Twilight Zone episode ‘Judgement Night’ a German U-Boat is part of a time loop, endlessly sinking a passenger ship, over and over again. The perfect situation for a Time Lord to try and fix.
The tv series ‘Seaquest DSV’ provides examples of how to mix submarines with science fiction, while the short lived ‘Last Resort’ explores the power that a submarine wields in the modern age and the ethical dilemmas its crew is forced to deal with.