In John Ashbery's early poem "The Painter", a serio-comic parable of artistic creation, the eponymous dauber sets himself the task of painting "the sea's portrait". Expecting it to "rush up the sand, and, seizing a brush,/ Plaster its own portrait on the canvas", this most Zen-like of painters sits passively on the shoreline. His compatriots try to goad him into action - choose something else for a subject, they say, something "less angry and large" - but it is nature itself that he wants on the easel, not his own narcissistic fabrications. When he eventually settles for a wholly white canvas, a howl rises from the seafront, and both painting and painter are hurled unceremoniously into the waves. A blank or nearly blank canvas may express the sea's nature more truthfully than pictures of waves and bobbing boats, but it also comes perilously close to letting something unspeakable into our midst.
It is the work in the first part of Tate Liverpool's new sea-fixated show - which is, in accordance with current Tate practice, divided into bland, bite-sized "themes" - that seems nearest to that of Ashbery's hapless painter. None of these artists (helpfully grouped under "Contemplation") opts for all-out whiteness, but a number of them give the sensation of gazing into a realm as little known as the blank spaces in 19th-century atlases. In Hiroshi Sugimoto's Day Seascapes, a series of black-and-white photos taken from clifftops around the world, the eye clutches at the thin horizon line and the waves' faint wrinkles as the only means of orientation. They do not offer much support, but they lend an austere and unexpected classicism to these images of near-total absence.
Chris Welsby's Drift, a video of what appears to be a busy shipping lane, lacks even this. The camera pans back and forth as if searching for something, and the grainy monochrome of the screen only adds to the feeling of vague formlessness. This is a modern-day equivalent of the maritime pictures of past centuries, the sea no longer being a wild blue yonder, but a neutral space plied by tankers and cargo ships. Still, Drift makes its dissolving power seem stronger than ever. Elsewhere in this initial section are the aqueous op-art panels of Sue Arrowsmith - evocations of bright, Ikea-built oceans a world away from Welsby's blurry void - and a selection of Rineke Dijkstra's shots of adolescents posing gauchely on deserted beaches. The latter are bleak restagings of The Birth of Venus, a pitiless photorealism replacing Botticelli's dancing lines.
On to "Threat and Danger", and the glistening seascapes of Gary Coyle. His Lovely Water series of large-format colour photographs documents his daily swims in an Irish cove. Taken from the perspective of the swimmer, presumably using a waterproof camera, they give a wonderful sense of immersion in a vast and ungovernable element. Yet, despite being stuck under this ominous-sounding banner, Coyle is almost the only artist in the show who seems to take any real physical pleasure in the sea. For the rest of them - whether it is James Peel's obsessive documentation of drowned civilians, Mariele Neudecker's entombed ships or Tracey Emin's shabby beach hut - the mood is primarily one of elegy and loss. Perhaps, in the drab surroundings of Liverpool's abandoned waterfront, that much is inevitable.
Martin Parr's West Bay photographs seem at first to provide respite, but these huge and luridly coloured holiday snaps ultimately convey a kind of mild hysteria rather than actual enjoyment. One shows a rack of postcards whose saccharine images - a poodle, a thatched cottage, a kitten, a steam train, shire-horses - suggest a neurotic need for reassurance and cosy nostalgia. Out at the sea's edge, eye candy is at a premium. Another photograph contains, in a brilliant reversal of the more accustomed image, a face-on "portrait" of a rapacious-looking seagull set against a background of squabbling humans.
The most bitterly pessimistic piece in the exhibition, however, is also the funniest. Rodney Graham's short film Vexation Island opens with a shot of a half-drowned sailor lying on the beach of a tropical island, his bloodied head resting on a cask. Beside him, perched on a similar cask, is the ship's parrot. The great sea booms and the sun beats down. It's a scene familiar from countless Hollywood films - the only difference being that, in this case, nothing really happens. When the sailor eventually rouses himself and shakes a palm tree in the hope of dislodging some food, he is quickly despatched by a falling coconut. The sea still booms, the sun still beats down and the man lies prone on the shore. And that, the film implies, is all we will ever know of paradise.
"At Sea" is at Tate Liverpool, Albert Dock, Liverpool L5 (0151 702 7400), until 23 September
