Finding good diving conditions in the UK can be a real challenge. With so many factors to consider—like underwater visibility, changing wind, strong swell, and unpredictable algae blooms—planning a dive can feel overwhelming.
The ever-changing weather and coastal conditions make it hard to know when and where the water will be clear and calm enough for a safe and enjoyable dive.
Here is a guide on what to look for in weather conditions to find good diving conditions in the UK.
1. Check wind strength and direction
Wind can make or break a dive. A gusty day can stir up the water and reduce visibility, not to mention make surface conditions choppy.
First, look for the wind speed. The lighter the wind the calmer the conditions. The small green arrow and lime arrow are under 3bft (12mph), which is up to a light breeze, and creates small sea wavelets. Once the arrow turns orange (4-5bft or 13-24 mph), small wavelets will start appearing. This can still be diveable, but proceed with caution.
Next, check the wind direction. This is especially important with higher wind speeds. You’re looking for off-shore wind. When the wind is coming off-shore, the sea by the shore is calmer as its protected by the land. The wind hasn’t had the distance to create wavelets. On-shore winds tend to create more chop, and also stir up the visibility.
Use Marla’s map wind overlay to check the wind strength and direction at each dive spot at a glance. Click on a dive spot to check the hourly breakdown of the wind speed and direction.
2. Check the swell strength and direction
Swell refers to the size and strength of the waves created by distant winds or storms. It can impact both the surface and underwater conditions of a dive. High swells can create rough seas, making it difficult to safely enter or exit the water, and can reduce underwater visibility by stirring up sediments. Even when the sea looks calm near the shore, the underwater effects of swell can still affect your dive. Lower swell means smoother water, making your dive more enjoyable and safer.
When checking the swell direction, you're looking for how the waves will approach the dive site. Ideally, you want the swell to be coming from a direction where it won’t hit the dive site directly, as this can create rougher conditions and reduce visibility by churning up sediment. For example, if the dive site is sheltered from the swell direction by a headland or natural barrier, conditions are likely to be much calmer.
In general, you’re looking for the least amount of swell at your dive site and swell coming from a direction that’s blocked or minimal to avoid rough seas and poor underwater visibility.
Use Marla’s map swell overlay to check the swell strength and direction at each dive spot at a glance. Click on a dive spot to check the hourly breakdown of the swell speed and direction.
3. Check underwater visibility
Good visibility doesn’t just make diving more enjoyable; it’s also essential for safety. It’s no fun—and potentially dangerous—diving when you can’t see what’s in front of you.
Visibility is impacted by a myriad of features. It’s not just the weather that plays a role—there are countless factors at work. Some, like tides and currents, are predictable, but others, like algae blooms, can appear overnight and completely change the visibility.
Even divers with years of experience are often caught out. As one seasoned diver put it: “I’m experienced at predicting visibility, but that doesn't mean I’m good at it."
That’s where Marla comes in— Marla’s AI model collects weather, coastal conditions, diver reports, and—most importantly—satellite data that tracks algae levels. All these key factors are analysed to create an underwater visibility forecast for anywhere around the UK and Irish coast.
This approach means we can provide accurate, daily, visibility forecasts for anywhere in the Ocean, without the need for expensive, hard-to-install sensors, or waiting for somebody to put their head underwater first.
Use the map visibility overlay to check the visibility forecast at each dive spot at a glance, allowing you to choose your dive site accordingly.
Marla will tell you how it thinks the visibility is at any dive site, and how confident it is in its forecast. You can also check the recent algae levels (measured by satellites).
4. Check the tides
Most divers aim to dive at the slack tide—the period between high and low tides—when water movement is minimal. This reduces currents and can improve visibility. The slack tide is different at different locations.
Rising and falling tides can stir up sediment, reducing visibility. Generally, diving just after high tide offers clearer water as cleaner, offshore water flows into coastal areas.
Tides create currents that can make a dive easier or more challenging. In areas with strong tidal currents, plan your entry and exit times carefully and dive with the current to conserve energy.
Some sites may be accessible only at certain tide levels, so ensure the entry and exit points are safe based on the tide timing. Lower tides can expose rocky areas, and higher tides may cover safety hazards or limit access.
You can check today and tomorrow's tide times in the Marla app.
5. Check local diver reports
There’s nothing like a report from a diver coming straight out of the water. Forecasts are never 100% accurate, so listen to divers who have been in recently. Divers can share knowledge about what marine life they saw, or anything to look out for on the dive.
Share your diver report after your dive! Help others know what it was like. Each report also helps improve the accuracy of the visibility model.
You’ll find reports in the ‘Diver reports’ tab in the Marla Blue app.
Marla Blue - Diving Forecasts
Marla helps you find the best undersea visibility, so you can experience the beauty the UK and Irish seas have to offer.
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Disclaimer
While Marla provides forecast information to help you find ideal diving conditions, these forecasts are not guaranteed to be accurate and should not be solely relied upon when planning a dive. As with all forecasts, they may not be 100% accurate. Please make sure conditions are safe before you get in the water.
Marla cannot account for currents or specific local conditions that might make diving dangerous. This list of conditions to check is not exhaustive, but is intended as a place to start.
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