READERS of contemporary poetry in America will welcome the publication of Alice Oswald’s Spacecraft Voyager 1, her first collection of poems to appear in the United States. Oswald, who works as a gardener in Devon, England, has an intense and exploratory relationship with the physical world. Like Robert Frost, she sees it through the eyes of a naturalist, recording the precise data of experience. Her obsessive subjects are light and water, particularly how they are manifested in the moon and sea. In “Sea Sonnet,” she writes,

So I have made a little moon-like hole
with a thumbnail and through a blade of grass
I watch the weather make the sea my soul,
which is a space performed on by a space;

and when it rains, the very integer
and shape of water disappears in water.

The centerpiece of the collection is a long and compelling lyrical narrative about the River Dart. This is a poem of cultural, social, and physical ecology — unlike anything I know — as it assembles both a description and history of the river through the voices of people who live and work along its banks and in its estuary. Dexterously inventive, Oswald moves effortlessly from rhymed couplets to prose to free verse as various denizens appear. The genius of “Dart” is in how human voices — a drowned canoeist, ferryman, an eel watcher, naturalist, chambermaid, waternymph, and many others — become the river itself, traveling on and through its current, and, at times, like light on water, reflecting its changing moods through a changing landscape.

While “Dart” is an ambitious tour de force, the three new poems at the end of the collection are utterly remarkable, especially “Dunt” — “a poem for a nearly dried up river.” In “Dunt,” a broken, glass-encased effigy of a Roman waternymph “tries to summon a river out of limestone.” The waternymph, like the river itself, is the vestige of a less degraded and savaged world, a world in which rivers were animated by particular spirits and whose waterways were true “fish path[s]” to the sea. “Dunt” reveals that while Oswald’s attraction to describing and naming the world is a manifestation of a deep and inherent optimism, she is also a subtle elegist for the planet.