Safety · Destination Guide
Train under a pier, drop onto historic wrecks, and surface beside the Jurassic Coast
Dorset is a capable but unforgiving cold-water environment. The central controls are local tide planning, adequate thermal protection, practiced DSMB use, conservative depth and decompression limits, and willingness to cancel. In a sea emergency, call the Coastguard on VHF Channel 16 or 999. For suspected diving illness in England and Wales, also use the British Hyperbaric Association National Diving Accident Helpline on 07831 151 523.
Mean Weymouth water reaches only about 17°C at its late-summer peak and falls near 7°C in February. A drysuit, hood, gloves, and appropriate underlayers are normal for many divers. Current can rise rapidly outside slack, especially around Portland and offshore wrecks. Wreck penetration requires specific training, a continuous guideline where appropriate, redundant gas and light, and an exit plan. Do not enter a restricted or unstable structure merely because an opening is visible.
At sea, alert the skipper and Coastguard on VHF Channel 16 or 999, administer the highest available concentration of oxygen through trained personnel, monitor airway and breathing, protect the casualty from cold, and follow medical direction. Do not descend again to treat symptoms and do not let a casualty drive. Diving symptoms can be delayed or subtle, so contact the National Diving Accident Helpline when in doubt.
Dorset County Hospital in Dorchester and Poole Hospital provide 24-hour emergency departments. Swanage Minor Injuries Unit and Weymouth Urgent Treatment Centre can help with suitable non-life-threatening problems during published hours, which should be checked on the day. They are not substitutes for 999 in a serious incident. The former Poole hyperbaric chamber closed permanently on 31 January 2025, so old guidebooks naming it are outdated. Do not self-select or self-drive to a chamber. The Coastguard, ambulance service, National Diving Accident Helpline, and receiving clinicians coordinate assessment and any transfer to a currently operational facility.
Slack water is site-specific
Many offshore wrecks and drifts cannot be planned from a generic tide time alone. Follow the local skipper's run time and briefing, descend without delay when instructed, and be prepared for a short or changing slack.
Channel weather can replace the itinerary
Wind direction, swell, fog, and visibility can cause a site swap or cancellation in any month. Keep qualification-appropriate sheltered alternatives and never pressure a skipper or shore leader to launch.
Cold water affects judgment and dexterity
Mean water falls near 7°C in late winter and remains cool even when the air feels mild. Use adequate exposure protection, shorten plans before shivering begins, and rewarm in dry windproof layers.
Visibility is variable
Swell, plankton, runoff, silt, and diver traffic can reduce visibility quickly. Maintain close team spacing, carry lights where appropriate, and agree lost-buddy, line, and ascent procedures before entering.
Dorset's coast is covered by overlapping Marine Conservation Zones, a Special Area of Conservation, wildlife sites, harbour controls, and local codes rather than one marine-park tag. In Studland's Voluntary No Anchoring Zone, use approved moorings or other lawful arrangements and never anchor into seagrass. Do not stand or fin on the bed. At Kimmeridge, follow the Seashore Code, avoid turning rocks or collecting wildlife, and observe the Wild Seas Centre's advice not to use fins on the marked trail.
Leave artefacts in place. Any recovered wreck material must be reported to the Receiver of Wreck within 28 days, even when ownership seems obvious. Military wreck designations differ: at a protected place, divers may generally look but must not touch, remove, or enter; a controlled site requires permission for any diving. Check the current official list and the operator's briefing before the trip.
Use established entries, secure gauges and alternate air sources, maintain neutral buoyancy, and avoid contact with kelp, reef, wreck growth, and sediment. Never chase seals, dolphins, seahorses, or cuttlefish. Take photographs without blocking an animal's route or encouraging others to crowd it.
Do Not Do This
Avoid entering when slack water is site-specific. Confirm local briefings before committing.
| Contact | Role | Phone | Availability |
|---|---|---|---|
| HM Coastguard and UK Emergency Services | Coastal, at-sea, and life-threatening emergency response | 999 or 112; VHF Channel 16 at sea | 24 hours |
| British Hyperbaric Association National Diving Accident Helpline | Emergency medical advice for suspected diving illness in England and Wales | 07831 151 523 | 24 hours |
| NHS 111 | Urgent medical advice when the situation is not immediately life-threatening | 111 | 24 hours |
| Dorset County Hospital Emergency Department | 24-hour emergency department in Dorchester | 01305 255541 | 24 hours |