The most common exposure mistake in Lebanon is not choosing a suit that is too thin. It is choosing a suit based on the surface temperature on a sunny morning, and then being cold from the middle of the second dive onwards.
Here is how to get it right.
What the water actually does
Beirut's sea surface temperature ranges from roughly 18 °C in late winter to about 29 °C at the height of summer.
That range spans two genuinely different diving experiences, and the transition is slower than the weather suggests — the sea warms and cools well behind the air.
| Season | Approximate sea surface temperature |
|---|---|
| Winter | ~19 °C |
| Spring | ~19–20 °C |
| Summer | ~28 °C |
| Autumn | ~26 °C |
Note the spring figure. April feels warm on land and the water is still cold. This catches people out every year.
The two things that change the answer
Depth
The numbers above are surface readings. Below the surface it is colder, sometimes noticeably so.
This matters enormously in Lebanon, because the diving worth doing is deep. The Souffleur at 38–40 m, the Batroun cement wreck at 35–40 m and the Alice B at 27–37 m are all substantially cooler than the boat.
A suit chosen for a 10-metre reef dive is not the suit for a 38-metre wreck on the same day.
Repetitive dives
Cooling is cumulative. You lose heat through dive one, sit on a boat in the wind in a wet suit through the surface interval, and start dive two already cool.
This is why divers say they were fine in the morning and freezing by early afternoon. It is not the water changing. It is them.
What to wear, month by month
| Period | Typical surface temp | Shallow dive | Deep dive / repetitive |
|---|---|---|---|
| Jan–Mar | ~18–19 °C | 5mm + hood | 7mm or semi-dry, hood, gloves |
| Apr–May | ~19–21 °C | 5mm | 5mm + hood |
| Jun | ~24–26 °C | 3mm | 5mm |
| Jul–Aug | ~28–29 °C | 3mm or shorty | 5mm for depth or repetitive |
| Sep–Oct | ~26–27 °C | 3mm | 5mm |
| Nov–Dec | ~21–24 °C | 5mm | 5mm + hood |
If you can only own one suit for Lebanon: a 5mm full suit. It covers most of the year, handles depth, and is tolerable in August. A 3mm is a summer-only suit here.
Fit matters more than thickness
This is the part people get wrong after they have got the thickness right.
A wetsuit works by trapping a thin layer of water against your skin, which your body warms. If the suit is loose, that water flushes and is continuously replaced by cold water. A loose 5mm suit is colder than a well-fitted 3mm.
What a good fit looks like
- Snug everywhere, with no baggy pockets — particularly in the lower back, behind the knees and under the arms
- Tight at the wrists, ankles and neck, which are the flush points
- Difficult to put on when dry. If it slides on easily it is too big
- Full range of movement once on. If you cannot reach your own valve, it is too small
Accessories that matter more than they look
Hood. A large share of heat loss is through the head. In winter and spring, essential. On deep dives in shoulder season, worth having. A thin hood packs into nothing.
Boots. Needed with open-heel fins regardless of temperature, and they prevent the cuts and urchin encounters that come with rocky shore entries on this coast.
Gloves. Winter comfort, and useful protection around wrecks where fishing line and sharp steel are common. Check whether an operator restricts them at particular sites.
Vest or rash guard. A 2mm hooded vest under a 5mm suit adds meaningful warmth at the core for very little bulk. This is the cheapest genuine upgrade available.
Signs you are underdressed
Watch for these on a dive:
- Shivering — the dive should end
- Your gas consumption rising for no other reason
- Fumbling with your hands
- Wanting the dive to be over
Cold degrades judgement before it feels serious, and it is a recognised factor in decompression stress. Ending a dive because you are cold is a good decision, not a wasted one.
For a first dive or a course
Course fees normally include suit rental, and centres will size you. If you are naturally cold, say so when you arrive rather than after the first session — it takes a moment to swap for something thicker, and it is much harder to fix a cold student halfway through a training day.
The wider gear question — what to own, what to rent, and in what order — is in buying dive gear in Lebanon. Conditions month by month are in when to dive in Lebanon.
