Nelson Haven is a large, sheltered harbor protected by the unique 13-kilometer Boulder Bank, a natural spit and the largest natural reef in the Southern Hemisphere. This formation acts as a breakwater, creating generally calm waters within the haven, making it suitable for kayaking and stand-up paddleboarding. The harbor offers expansive views of Tasman Bay, the Western Ranges, and Haulashore Island. A primary and popular launch point for paddlers is from Tāhunanui Beach, which provides a shallow, gradual slope for easy access. Paddlers frequently undertake trips to the historic Nelson Lighthouse, situated on the Boulder Bank. This lighthouse, erected in 1861, is a Category 1 historic place and offers panoramic views. The harbor entrance through "the Cut" is noted to have a significant tidal range of 4 meters and can be dangerous, indicating that paddlers should be aware of strong currents and potential hazards in this narrow, curved channel, especially when transiting to or from open Tasman Bay. The area holds cultural significance for local Māori, with the Boulder Bank featuring prominently in stories and legends. Guided paddle tours, including night tours, are available, and equipment hire is offered locally. The overall paddling experience is characterized by scenic, protected waters with direct access to a notable historical landmark, though careful tide and current planning is essential for ventures near the harbor entrance.