Monique Roffey has established herself as a fearless writer with her choices of subject and her visceral style. Her entrancing memoir about sexual desire, With the Kisses of His Mouth, is a subversive work that transcends the author's personal story: it stands alone in the chasm that has opened between feminist literature and the belles du jour brigade. Her Orange-shortlisted novel The White Woman on the Green Bicycle is similarly defiant. Set in her native Trinidad, it is an exploration of a marriage and a country breaking down in parallel  and despite the sensuous prose, politically it cuts no slack.

Archipelago travels to new, intoxicating latitudes. It comes as no surprise that a real-life event sparked off the idea for this novel: the flooding of her brother's house in Trinidad in 2008. Two years later, Roffey embarked on a boat journey from Port of Spain through the Panama Canal and to the Galápagos. The result is an adventure blazing with a lust for life.

In the wake of a flood which destroys his house, kills his baby son and leaves his wife doped on antidepressants, Gavin Weald is left in charge of his six-year-old daughter, Ocean, and dog Suzy. The cause of the flood is half climate change, half local politics, and Gavin is so full of anger and grief that he is unable to carry on. So one day, he packs some bags, grabs Ocean and Suzy, tosses his mobile phone into the sea, and sets off in Romany, the yacht from his bachelor days. We know we're in for a fraught adventure because Romany is haunted by the ghost of its unknown previous owner, and because Gavin may have suffered but has plenty left to lose. "Fat men don't sail," he frets as they set off. "When did he get fat? He has some other image of himself, a long-ago younger man image, the one that had a gift for the sea."

The thrust of the story is both geographical and psychological. Roffey excels equally at the hands-on descriptions of yachting, the intricacies of island navigation, the beauty and terror of the sea, and the inner life of her rudderless protagonist. The girl is captured with pitch-perfect empathy: "She is quietly working out how many different types of loss might exist. Many, my little mermaid. Many." The monotony of their journey is never monotonous  there are encounters with sailors, such as the gone-native Scandinavian skipper Phoebe ("Romany is a one-word poem," she tells Ocean) who spends just long enough with them to get to Panama and for both man and girl to become painfully attached. There are dodgy drifters, accidents, memories and metamorphosis: "Gavin feels awkward in his straw hat and new bushy beard, with his child and his dog, like they are a group of refugees or they have come from a festival on the sea. Ocean's hair is pearl-silver " There is the trance-like derangement of 10 days without land: "He sits for hours  many people appearing and vanishing in a haze  They all pass before him, his old life, his real life, they all come to say hello." There is also a symbolic  but all too real  tsunami.

Half the joy here is the experience of life on a boat: "Just the sea around them, alien and natural, sheets of silver-blue, flat and calm for now, spread out like a vast wealth." The other half is riding the waves with an open mind to discover where Gavin and his crew wash up, so I won't give it away. But look out for the astonishing scene with the albino whale "wailing like a cat or a man driven mad by grief", which is the centre of this big-hearted Moby-Dick story for our times.

 Kapka Kassabova's Twelve Minutes of Love: A Tango Story is published by Portobello.

Grief is tidal. It can sweep a person away, suck them down and submerge them completely. In Monique Roffey's compelling new novel Gavin and his six-year-old daughter, Océan, have suffered a family tragedy with which both are still struggling to cope. Gavin's answer is to leave their Trinidad home behind and take to the water with his young daughter and their old dog Suzy in tow.

The novel takes the form of a journey, the purpose of which is at times unclear; Gavin and his daughter head out for the Galápagos but the destination always feels secondary to the act of getting there. Roffey, herself from Port of Spain, writes like one who knows these waters well, their beauty and their capacity to cleanse, but also their volatility.

The writing is studded with striking images  the dog's nose is as pink as a scrap of ballet shoe  and there's a real sense of momentum, of Gavin's deep need to keep going. Roffey is adept at conveying wonder, of the father and daughter both, at the things they encounter along the way, and if the final wrapping up is a little too neat, the journey is what counts here, the journey is all.