Submariners shivered. Or they sweated. Occasionally, they were comfortable. The problem was the tendency of a submarine to remain the same temperature as the ocean around it.

In a surface ship, the majority of the ship is above the water line, usually. Modern warships are especially lightweight. A submarine running on the surface shows no more than a tenth of its volume. The rest of the mass is in direct contact with the water, and is the same temperature as the water, even on the surface.

In the Caribbean, that meant that the submarine was warm. The engine room was like a sauna. To cope, the enginemen re-routed the combustion air for the diesels so that it entered the compartment on the opposite end from the air intakes on the engines. That produced a strong, warm breeze through the compartment, and some relief for the watchstander who was there for four hours at a time.

The rest of the boat was warm as well. The control room and the berthing compartments were just plain hot. The galley, and the adjacent crew's mess, were miserably hot. The cooking equipment threw off a lot of heat, and the ventilation system on a submarine is quaint, not effective.

The torpedo rooms became popular hangouts in tropical waters. The poker and craps games from the crew's mess migrated to the small area at the breeches of the torpedo tubes. There was very little equipment to generate heat in these compartments. The massive bronze torpedo tubes stuck half into the room, with the other ten feet or so submerged in sea water. People tended to lean against the tubes, or drape themselves over the tubes, to get a little heat drawn off by the 75 degree metal. I tried it a few times, and it helped a lot, especially with my mental abilities. When I got that hot, for that long, I couldn't think very well. Most people couldn't. After twenty minutes with my forehead on the big bronze tubes, I could actually do the calculations necessary to balance the submarine fore and aft, and overall.

Our uniforms became less and less formal in this heat and humidity. All through the boat, we found excuses to hold onto valve handles or the garbage disposal or something that would draw off our body heat, dissipating it into the sea. Every compartment had a bilge, with its residual water, so the humidity was always very high. The most common memory from those trips was the sweat.

This is all in the past tense now, at least for the U.S. Navy. A co-worker recently pointed out to me that the USS Blueback, the last of our conventional submarines, has been retired. The newer, nuclear powered submarines are built with less surface area for a given amount of space aboard the ship. They have much more modern insulation. And they have enormous amounts of waste heat available from the nuclear reactors. A lot of this waste heat is routed to absorption chillers, which produce lots and lots of air-conditioning for the crew.

We had small air conditioners on my boat. Their main function was to reduce the humidity slightly. They never accomplished much in the way of cooling.

Of course sometimes we were not in the Caribbean, but at the Arctic Circle. Even in the summertime, the water in this part of the world stays at 29 degrees, all the time. The boat got cold. We got cold. We wore jackets. We found pretexts to visit the engine room, if we were on the surface or snorkeling. We wore extra socks and long underwear. For bridge watches, we had parkas, and we had coffee delivered to the bridge frequently. We put extra blankets on the bunks, and we spent more time than usual in the bunks. We read books in our bunks, rather than watching the movie or playing cards. Once, after we had been submerged for a significant length of time, we turned off the air-conditioner. Almost immediately, dew began to form on sections of the torpedo tubes. All entertainment centered in the crew's mess The cook was constantly having to eject sailors from the galley, where they were warming their hands over the meal as it was still being cooked.

One one of these cold arctic dives, after sixteen hours of running on the battery, we got an urgent message to surface and stand by to pick up an aviator in case someone ejected and was in the cold arctic water. We did so, at some damage to our engines. Our engine lubricating oil was not designed for such cold temperatures, and normally we would have turned on some heating elements in the sumps an hour before we turned on the engines. We raced to the coordinates that we were given, but a helicopter got there when we were still half a mile away, so we were not needed. It was just as well, since we did not have facilities to warm up someone pulled from that water. Our crew congregated in the engine rooms, and played poker in pantomime for an hour, unable to speak over the roar of the locomotive diesels.