When planning a scuba diving trip to Costa Rica, most people think about warm tropical water. And yes, the Pacific coast of Guanacaste can be very warm. But water temperature changes throughout the year, and it can feel different once you descend.
So, if you are diving in Las Catalinas, should you bring a 3 mm or a 5 mm wetsuit?
The answer depends on the season, the conditions and, perhaps most importantly, how easily you get cold.
How warm is the water in Las Catalinas?
Water temperatures around Las Catalinas can range from the low to upper 20s Celsius depending on the time of year and conditions.
During the warmer months, surface temperatures can reach around 28 to 30°C (82 to 86°F). During the cooler season, temperatures can drop, particularly at depth, where you may encounter noticeably colder water.
Seasonal changes are influenced by winds, currents and upwelling along Costa Rica’s Pacific coast.
This is why the temperature you see for the ocean surface is not always the temperature you will experience throughout your dive.
3 mm or 5 mm wetsuit?
For many divers visiting Las Catalinas during the warmer months, a 3 mm full wetsuit is a comfortable and versatile option.
During cooler periods, or for divers who tend to get cold, a 5 mm wetsuit can make a significant difference in comfort.
As a general guideline:
| Season | Wetsuit to consider |
| December to February | 5 mm for colder divers, 3 mm for those who run warm |
| March to May | 3 mm |
| June to August | 3 mm or lighter, depending on comfort |
| September to November | 3 mm or lighter, depending on conditions |
These are guidelines rather than strict rules. Ocean conditions can vary, and every diver experiences temperature differently.
A diver who feels comfortable in a 3 mm wetsuit may find a 5 mm unnecessary, while someone who gets cold easily may be much happier with the extra protection.
There is no prize for wearing the thinnest wetsuit possible.
Being comfortable underwater allows you to focus on your buoyancy, your breathing and the experience rather than thinking about how cold you are.
Why can Costa Rica’s Pacific feel cooler than expected?
One of the surprises for visitors is that the air temperature and water temperature don’t always tell the same story.
You can be enjoying a warm, sunny day in Guanacaste and still encounter significantly cooler water during a dive.
Seasonal winds and upwelling can bring deeper, cooler water closer to the surface. This is particularly noticeable along parts of Costa Rica’s Pacific coast.
You may also experience a change in temperature as you descend.
For this reason, choosing your wetsuit based only on the weather forecast is not always the best approach.
What should you bring?
If you are traveling to Guanacaste for diving, a 3 mm full wetsuit is a good all-around option for many divers, particularly during the warmer months.
If you know you get cold easily, are planning multiple dives or are traveling during the cooler season, a 5 mm wetsuit may be the better choice.
If you are renting equipment, you don’t need to guess before your trip. Your dive operator can recommend the most appropriate exposure protection based on current conditions and your personal comfort.
Diving Las Catalinas with ConnectOcean
ConnectOcean departs from Flamingo Marina for dives around Las Catalinas.
Before every trip, our team considers the conditions of the day, including water temperature and the planned dive profile, so you can be properly prepared before getting in the water.
Because the goal isn’t to wear the smallest wetsuit possible.
The goal is to be comfortable enough to forget about the wetsuit and enjoy the dive.
