The lands and waters of Nelson Lakes hold deep significance for many Maori nations. The lakes feed rivers that run through territories belonging to Ngati Apa ki te Ra To, Ngati Kuia, Rangitane o Wairau, Ngati Rarua, Ngati Tama ki Te Tau Ihu, Ngati Toa Rangatira, and Te Atiawa o Te Waka-a-Maui. Before them, Ngati Tumatakokiri lived in the region. Pressure from Maori groups to preserve land, combined with support among Pakeha for the national park movement, led to the park's creation under the National Parks Act of 1952. Nelson Lakes was one of four national parks established in the 1950s, alongside Fiordland in 1952, Mount Cook in 1953, and Urewera in 1954. New Zealand's first national park, Tongariro, had been set aside in 1887, but the idea of systematic protection took decades to mature into legislation. The park is bounded to the west by the Alpine Fault, the same fracture line that drives earthquakes across the South Island, a reminder that this landscape is still being made.

Three species of beech dominate the park's forests: mountain beech, red beech, and silver beech. Together they create a canopy that supports threatened kaka and kakariki, along with a broader community of birds, amphibians, and insects. But the ecosystem faces a relentless invader. Wasps, drawn to the honeydew produced by scale insects on beech bark, have established dense populations that compete directly with native birds and insects for this critical food source. The Rotoiti Nature Recovery Project, a mainland island initiative covering 5,000 hectares of beech forest around Lake Rotoiti, targets wasps along with stoats, possums, and rodents. The results have been encouraging: predator numbers have dropped on the eastern side of the lake, and it is now possible to see great spotted kiwi, South Island robins, bellbirds, fantails, rock wrens, keas, and paradise ducks in the area. Julius von Haast wrote in 1861 that the weka was everywhere in the region, from grassy plains to alpine summits. By the time of the recovery project, the western weka had become rare.

Some of the park's most compelling stories belong to species that are disappearing. Hundreds of South Island kaka lived around Lake Rotoroa by about 1900. Through the twentieth century, their numbers fell steadily until by 1991 it was rare to see groups of more than five or six birds. The South Island long-tailed bat tells a similar story. In 1900, the bats were a common sight in the park, so prevalent that a spot near St. Arnaud was known as bat cutting. By 1930, observers noted they were declining. By the 1990s, the species was classified as rare. Trampers still occasionally glimpse them at dusk, but the colonies that once numbered more than a hundred have dwindled to scattered individuals. Then there is the Cupola gecko, a grey-brown forest gecko with distinctive V- or W-shaped bands across its back. So rarely seen that scientists were not certain it still existed, four individuals were found in the Sabine Valley in 2021, confirming they persist in alpine regions. Each rediscovery is a small reprieve, not a recovery.

Nelson Lakes contains 20 Department of Conservation huts, ranging from basic bivvies to serviced shelters, and the most popular destination is Angelus Hut, perched beside a lake that freezes over in winter. The hut's scenic location and the relatively easy access to Robert Ridge from the village of St. Arnaud tempt trampers into underestimating the difficulty. Snow and poor weather can arrive at any time of year, and in winter all four routes to Angelus Hut are typically covered in snow and ice. In July 2018, a tourist died of hypothermia while tramping alone near the hut, prompting new safety initiatives. The Mountain Safety Council now encourages inexperienced trampers to avoid solo trips in alpine conditions, to carry emergency shelter and navigation equipment, and to bring a communication device. The park's peaks range from 1,800 to 2,300 metres, with two permanent snowfields on Mt. Ella and Mt. Hopeless representing the northernmost such features on the South Island. The names, as at Cape Foulwind down the coast, tell the truth about the place.