Lake Rotoroa is located in Nelson Lakes National Park in the Nelson/Tasman region of New Zealand's South Island. At approximately 14 km long, about 2.4 km wide, and 140 metres at its deepest, it is the largest lake in the park. The lake is fed by glacial water and is surrounded by mixed beech-podocarp forest. To reach it, turn off State Highway 6 at Gowan Bridge and follow an 11 km sealed road up the Gowan Valley to the lake end.

The main access point has a boat ramp, jetty, and parking area. A campsite with tent sites is available at the lake for paddlers planning overnight trips. The campsite operates on a first-come, first-served basis, with fees of $15 per night for adults and $7.50 for children aged 5–17. Fires are not permitted at any time, and dogs are not allowed. Water taxis operate on demand at the lake, which can be useful for shuttles.

The primary paddling route runs the full length of the lake, approximately 14 km, connecting the main access point to the D'Urville Valley hut at the far end. Paddlers typically keep close to the western shore, where submerged trees, small side streams, and pocket beaches offer points of interest along the way. The full length can be paddled in roughly two and a half hours under calm conditions. The water is notably clear, with visibility to the lake bed.

Jet skis and similar personal watercraft are prohibited on the lake, and waterskiing is also not permitted. Power boating on the park's rivers is likewise banned. Kayaks and canoes can be hired from Rotoiti Water Taxis year-round, though this service is based at the other park lake, Lake Rotoiti.

Sandflies are described as ferocious at the lake, and insect repellent is strongly recommended. The water temperature can be very cold, particularly in cooler months, and paddlers should be prepared for numb hands even in conditions that appear calm. The lake is known for its reflective surface and crystal-clear water, with the surrounding beech forest providing a consistent backdrop along the shoreline.