Apart from the obvious answer, which would be that it’s colder, there are a few things to know and consider before diving in cold or cooler water than you are used to.
Cold Water © Dave Briggs
- Exposure Protection
It might be obvious, but you will need to adjust what you are wearing to counteract the cooler temperatures and stay comfortable. This could mean adding a vest and hood, using a thicker wetsuit, or wearing a dry suit. A thicker wetsuit is going to mean you need to increase the amount of weight you are carrying and will lead to greater buoyancy shifts as the material compresses and expands upon ascent and descent. With a thicker wetsuit, you might even notice wrist mounted gauges and fin straps loosen as you descend. Diving with a dry suit isn’t a hard skill to master, but you do need extra training, you will wear significantly more weight than a wetsuit which makes the dive overall more tiring. For more on this subject read our tips on staying warm. - Decompression Limits
Regardless of where you are your body’s reaction to being cold is to pull the blood from your extremities to pool around your vital organs. This response is the reason why your hands and feet are noticeably more chilled as these areas are not your body’s priority in term of survival. This circulatory effect is why, for decompression limits, you are advised to be more conservative with your plan when diving in cold water. The theory is this effect will alter the way that you on and off gas. (This reaction is also one of the reasons you need to pee while diving.) - Air Consumption
When you are cold, your body also burns more calories to stay warm. This process uses oxygen so your breathing rate would naturally increase. Further, as you are using more weight and causing more drag, you will be working harder underwater which again works to increase your breathing rate. These factors mean that divers use more air when diving in cold water. - Gloves
Yes, these seemingly minor things have a section all of their own. That’s because your dexterity is fundamental to most things. Add a thin pair of gloves, and you might have difficulty freeing hair from your mask skirt. Add a thick pair of gloves and anything from adjusting a fin strap to using a camera or deploying an SMB become tasks that almost require relearning. - Gearing Up
Mainly due to exposure protection, this is going to take longer and does need a little more thought. Thinking about the added complexity gloves bring to the activity you do want to make sure you have a plan for a logical process of gearing up. Do remember that not all cold water diving takes place in cold air temperatures. South Africa is a good example of this; you want to make sure that you gear up at the same rate as your buddy so that you are both ready to enter the water together. Overheating in a drysuit in bikini wearing temperatures is not a great way to start a dive. - Equipment
Apart from what you are wearing to stay warm, the only other consideration is the regulator that you are using. Make sure it’s suitable for cold water to avoid ‘freezing.’ Free flowing should be avoided and there are recommendations against purging or inhaling and inflating your BCD at the same time so as to reduce the load on the first stage. - The Shock
No matter how much you prepare mentally, you are going to experience that ‘yikes’ of cold water. Even in a dry suit your face is still exposed and clearing your mask can leave you gasping. - Marine Life
Yes, that’s different too. Most mammals inhabit cold water, so if you want to go and play with seals, you best be ready to brave the cold. There are many different playgrounds to explore; kelp forests are wondrous, and ice diving has some spectacular vistas.
