Not just an absorbing love story but also the story of a young woman determined to confront and overcome her past by swimming the treacherous mouth of the River Humber.
The descriptions of the light and water are superb and the swimming scenes leave you feeling exhausted but triumphant.
She trod water for a few seconds, struggling to get a grip, but still couldn't bear to immerse her face. Fred had told her that a person's face - under the eyes - was particularly sensitive to cold. The coldnewss swiped at her like a hard slap. She struck out, webbing her fingers against the icy water. Looking down through her goggles into the depths, she could see nothing, only volumes of blackness, no guiding lines like the rows of coloured tiles in the pool. Panic started in her solar plexus and echoed in her chest like discordant music. Anything could lurk down there in that blackness - dead creatures, the skeletons of birds, rusting mattresses, flotsam tipped into the dock to rot; cargoes dropped from long-broken-up vessels. And coating everything would be black mud, smooth as melted chocolate. Last week the newspaper described how a man and his daughter were stranded out on a beach, sinking into mud as the tide raced in. The little girl was drowned.
Nick in the boat waved at her. "All right?" he shouted.
She tried to grin back. "Okay," she mouthed, and made herself kick out in breaststroke, now daring to dip her face into the water. Concentrating on her stroke and the glide of her body, she moved forward. As she swam, she tried to avoid dwelling on the coldness and strangeness of everything, but she still felt breathless and terrified. Dave was right - it was totally different from swimming in a pool. The pool was intended for swimmers, the dock for ships, huge ships. Its size dwarfed - you felt you were a cork bobbing on an ocean. But this was nothing compared with swimming in the estuary and the North Sea. This was just the first stretch of open water to overcome.