What wesuit did I take? When we go on a diving trip, this is one of the most common questions that comes to mind. One of the many doubts that can arise is precisely in relation to the temperature of the water that we will find in destination and the weights that we will need to dive. Given that each sea has a different density, it is not the same to dive with a 5mm wetsuit in the Mediterranean than with a lycra in the Maldives. Here we are going to see how all this is going.

One of the first things to keep in mind is that in the vast majority of destinations, the tanks that we will find are aluminum 12L. These tanks when they reach 100 bars of pressure become positive, that is, they “pull” to the surface like demons. So from the start we have to add approximately 1kg to our usual ballast that we would use with the same suit and steel tanks on Mediterranean coasts.

Once we are clear that we are going with an aluminum tanks and what that implies, we will see what I tried to put on depending on the water temperature. Considering that each person has a different resistance to cold and that as we know from the diving courses we have done, our body in the water will lose approximately 25 times faster heat than if we were on land, in a general way we can say that if dive in warm water will suffice with a 2 or 3mm wetsuit or a lycra and if we do in colder waters we will have to opt for a 5mm 7mm wetsuit or even a dry suit. Having said that, the question comes alone … that with warm waters? From 21º we can talk about warm waters and from 25º very warm waters. Between the 21st and the 27th we can dive with a 3mm, with or without a thermal undershirt, depending on the tolerance of each to the cold. From the 25th with a 3mm, a 2mm, a shorty or even with a lycra we will have enough. I particularly from the 25th with a trousers suit and a good thermal protection shirt I manage. The less neoprene less ballast I will need and it is also more comfortable to put on and take off, especially in the liveaboards in which you usually do several dives per day.

If we go down from 21º degrees to about 16º we will need a 5mm wetsuit and between 16º and 10º a semi dry of 7mm will be the most appropriate. Although I have seen people with dry suits in the Red Sea, and I speak of recreational dives at a shallow depth, it is usual to leave this type of suits for waters below 16º. In the following table you have a more visual idea.


water temperature suit table

Well now that we are clear that the safest thing is that we go diving with aluminum tanks to which we must add 1kg of ballast and the recommended wetsuit depending on the temperature of the water that we will find, there is another variable that It will influence the ballast we put on our belt / jacket, and that is the density of the water.

When we talk about water density, it is not the same to dive in the Red Sea that has a higher density than in the Indian Ocean where the density is lower. With the same equipment, suit and weights, in the Indico we will sink well while in the Red we will float …

Without going into heavy details of physics and chemistry, we will say that as is known, the density of the sea is determined by the amount of salt it contains, that makes it cost us more or less to sink. As a general fact (I have already said that I do not want to enter physics / chemistry), I will tell you that of the seas in which we are going to dive, (I am going to focus only on the warm ones) the Red Sea is by far the density all and in which we will need more weights. Also say that the “red” is denser in the North and less in the South, so there is some additional variation between diving in the Strait of Tiran or South Sudan. Usually we have to put a couple or three kilos additional to what we would need in the rest of the warm seas. For example, if we go with a 12L aluminum tank and a 3mm wetsuit we will need a minimum of 6kg to go down (depending on the anatomy of each one). If we put a 5mm or more in the Red Sea we will need an important amount of ballast, 8kg or even more to not look like buoys.

In terms of density, the next sea where it will cost us the most to go down is the Pacific, although notably less than the Red Sea, it is denser than the rest. Here we need about 2 kg less than in the Red Sea approximately, always depending on each one, type of suit, tank and tastes of each one, for example I like it more than it costs me to go down a bit but then during the dive to be more comfortable, there are those who prefer to go more ballasted to not make a balloon at the end of the dive, etc., etc.

Finally, the least salty of the warm seas is the Indian Ocean. Here without a shorty or a 2mm normally with about 4kg we will have enough, even in some areas like the Maldives and if you are thin / 3kg. This is clear depending on the anatomy of each diver, because the more overweight we have more kilos we will need.
And this is all I can tell you …

By Sergi García