A rig worker who suffered severe head injuries in a 20ft (6m) fall has been airlifted to hospital.
The drilling rig was being towed 20 miles (32km) offshore from Portland in Dorset early on Sunday morning when the accident happened.
Portland Coastguard helicopter managed to land on the rig despite rough sea conditions and storm force winds.
The 22-year-old man was airlifted to the specialist neurological unit at Southampton Hospital for treatment.
A spokesman from Portland Coastguard said: "In very difficult conditions the crew were able to land the helicopter onto the rig's landing platform 112 feet above sea level in pitching seas and high winds.
"The derrick [the framework holding the drilling machinery] on the rig would make winching a casualty too dangerous so a landing was required."
The rig was on tow to Las Palmas.