Kauai is known as the "Garden Isle" due to its vast tropical plant life. Three of the five US national botanical gardens are located on the island, featuring indigenous and ancient vegetation. These include Limahuli Garden & Preserve, Allerton Garden, and McBryde Garden. Limahuli Garden features over 1,000 acres of gardens in the Limahuli Valley, while Allerton Garden has over 100 acres of oceanfront gardens. McBryde Garden focuses on endangered Hawaiian species and has research collections. Other notable gardens on Kauai are Smith's Tropical Paradise, Kukuiolono Park, and Na 'Aina Kai Botanical Gardens.