The sea snake, serpent of the sea, is a highly venomous creature, its venom is ten times more potent than the cobra. Many native fishermen die from sea snake bites in the islands north of Australia, but, fatalities are rare in Australia. The sea snake does give its victim a chance to survive. It mouths its prey before it bites. The venom is slow to take effect, but, without treatment it causes flaccid paralysis - the victim simply goes to sleep and dies. Marion Reef is a coral atoll in the Coral Sea, 200 miles off the central Queensland coast, and home to a variety of sea snake species. Its blue waters are unbelievably clear - 50 metres visibility is the norm. The corals are luxuriant, sharks present, and its coral islands are like emeralds in a rainbow sea. It's a Garden of Eden with its own special serpent. Marine scientists accompany Ben Cropp on his vessel Freedom to Marion Reef. A great deal is yet to be learnt about the behavior of sea snakes. Tagging is one scientific program on the expedition's agenda - a dangerous and dramatic program for it brings out the worst in the sea snakes. They are angry when captured and even angrier when tagged and released, often venting that anger by attacking the diver. Mating time is another dangerous moment for scientific observation. The snakes entwine in a rhythmic courtship and resent any intrusion. Ben Cropp has experienced their aggression when moving too close with his camera, and had to fight off a most persistent attack. Otherwise, without human intervention, sea snakes appear to live a placid life in the coral lagoon, surfacing for air perhaps every half hour. Their enemies are few - mostly sharks and groper - and their fish prey plentiful which they hunt with myopic vision. It's the myopic vision which makes the sea snake boldly and blindly attack when molested, or curiously crawl over a diver if he freezes. The latter is the better way to meet the sea snake at close quarters, if the diver has the courage to keep very still. This film is a scientific adventure into a remote area of the Coral Sea, revealing the special life of the serpent of the sea.