In 1968 The Sunday Times announces the first non-stop, single handed round-the-world sailing race. The rules state that anyone who attempts a non-stop circumnavigation is automatically entered. There are two prizes; the Golden Globe for the first man home and £5,000 for the fastest voyage.  Competitors are told they must leave before the 31st October to avoid the full fury of a winter spent in the Southern Ocean –- the seas below 40̊ South where strong westerly winds collide with icy currents from the South Pole to create relentless storms and freak violent waves and troughs.

Donald Crowhurst is a 36- year- old father of four whose marine electronics business is ailing, and who feels compelled to attempt to win the fastest voyage prize, leaving behind his wife and young children. He is certain that a trimaran, the newest and quickest boat available will secure him the fastest circumnavigation.  Local businessman Stanley Best agrees to fund the build on condition that should Crowhurst fail to complete the voyage he must buy back the boat.  If Crowhurst retires from the race he faces financial ruin, he will lose everything, including the much-loved family home, Woodlands.

On the behest of local PR guru Rodney Hallworth, Crowhurst agrees to set sail from Teignmouth and names the boat Teignmouth Electron.  But Donald struggles to make the boat seaworthy for the October 31^st deadline.  His innovative designs, including a self-righting mechanism designed to bring the boat upright in the event of a capsize remain unfinished. Clare Crowhurst has enormous confidence in her husband’s ability but is nervous of the massive challenge he has undertaken. The pressure for Donald to succeed is intense and he becomes increasingly withdrawn as the departure date draws near. The preparations descend into chaos and when Donald finally leaves on the 31^st October deadline, his unsorted provisions are still strewn over the deck and cabin. Even as he sails out of Teignmouth he must endure a humiliating return to harbour when his anti-capsize air bag becomes tangled in the rigging.

Crowhurst makes slow progress during his first two weeks at sea. Teignmouth Electron shows her weaknesses and the hatches are leaking. Donald now faces an impossible dilemma; to continue into the Southern Ocean with no viable way of bailing out a leaking boat or to return home and face certain bankruptcy. For now he continues to meander down the Atlantic.

By the end of November only four competitors remain in the race, Robin Knox-Johnston and Bernard Moitessier are heading toward New Zealand, and naval commander Nigel Tetley is making good progress in the Southern Ocean. After his depressingly slow start Crowhurst starts to radio a series of increasingly record-breaking daily distances to his delighted press agent Rodney Hallworth who spends no time embellishing the mileages before relaying the good news on to Fleet Street. At home Donald’s family are thrilled by his sudden progress, his children believe he has a real chance of winning the £5,000.

In reality Crowhurst is slipping further and further behind his stated position. His logbooks show how the gap between his actual position and his imagined one has opened up.  He starts a second logbook where he records his true position and a list of elaborately calculated false positions on spare sheets. He is now weeks away from where the rest of the world thinks he is.  In effect, Crowhurst has become trapped by his own lie, unable to retire without being found out but knowing that to enter the Southern Ocean in a leaking boat would be suicidal.

Knox-Johnston and Moitessier are battling to be the first man home but after rounding Cape Horn, Moitessier sends a message back to his wife, Francoise, saying that he is going to continue round the world a second time –- for him, the journey is everything and the destination nothing. This leaves the way clear for Knox-Johnston to claim the Golden Globe for the first man to sail alone and non-stop round the world.  Thousands of well-wishers turn out to watch his triumphant return to Falmouth and on April 22nd 1969 Knox-Johnston takes his first steps onto land after more than 10 months at sea.

The two trimarans now battle for the £5,000 prize money.  Clare who has heard nothing from Donald for weeks fears for her husband’s safety.  But Crowhurst, who has been cruising off South America, makes an illegal landing in a remote Argentine bay.  A local coastguard unaware of his predicament gives him the timber and screws he needs to make vital repairs to Teignmouth Electron before Donald heads back out to sea.

Tetley and Crowhurst are now competing to be the fastest in the eyes of the world – the Navy man against the inventor, both in trimarans, both heading back up the Atlantic. In an effort to avoid his logbooks being scrutinized by the race judges Crowhurst is keen to come in a close second.  After re-establishing radio contact with Rodney Hallworth (for the first time in three months) he sends a message confirming that he will be unable to catch up with Tetley. Donald’s family is ecstatic that he is safe and on his way home.  Clare begins to get ready for her husband’s return and wonders if there will be a change in his personality after nine months spent on his own.

Tetley, believing that Crowhurst is right behind him pushes his boat so hard that it breaks up beneath him.  He is rescued off the Azores.  This leaves Crowhurst the certain winner of the race.  He knows that if he gets back to England his fraudulent journey will be exposed and he will face total humiliation.  As the world prepares for his triumphant return, Crowhurst stops sailing and starts to write a 25,000 word tract on God, human history and time travel.  He starts counting down to the moment he will attempt to think himself into a “‘cosmic being”’, and sets a time for when he will resign “‘the game”’ of being a human. 11 o’clock, 20 minutes, 40 seconds.  Crowhurst lays out his logbooks and sound recordings in his cabin before stepping off the side of his boat after 243 days at sea.

Clare is told that Teignmouth Electron has been found abandoned in the Atlantic.  As the grief stricken family struggle to come to terms with Donald’s death, Rodney Hallworth flies out to collect Donald’s logbooks and film recordings.  Hallworth informs Clare that her husband never went round the world and he sells the logbooks to a national newspaper.

Crowhurst’s body is never recovered.  Teignmouth Electron lies rotting on Cayman Brac in the West Indies.

DEEP WATER uses Donald Crowhurst’s original 16mm films and tape recordings to re-construct his extraordinary journey.  Much of this incredible archive has not been seen for over 30 years and was only recently re-discovered by the production.