The location has a high biological value, as it shows a high degree of biodiversity. That is because the Park is a sheltered bay with pristine water quality, so that it provides a good marine environment for housing a great variety of marine organisms. Numerous kinds of corals can be ascertained under the sea, and it is a hot spot for diving. So as to keep the local ecosystems away from human intervention, fishing, particularly bottom trawling and uses of dynamites or poisons like cyanides, collecting sea products and corals are prohibited by law.
Covering an area of around 2.6 square kilometres, the seaward boundary of the Park is demarcated by linking the tips of Heung Lo Kok and Kwun Tsoi Kok through the northern end of Flat Island and . The landward boundary follows the high water mark along the coastline.
Like the nursery grounds in Mai Po, Ho Ha Wan also offers a mangrove community occupying about 5,300 square metres. Along with a buffer zone between the tidal waters and the land, the mangrove woods are commonly act an ecologically sustainable habitat for juvenile fishes and other intertidal and subtidal invertebrates.
Hoi Ha Wan Marine Park has lush coral communities. Most of the stony coral species recorded in Hong Kong can be found in this marine park. 100-odd species of reef-associated fishes have been recorded in Hoi Ha Wan. In addition, records of wide variety of marine animals, like starfish and jellyfish, in the Park further demonstrates its ecological significance.
Reef Check through AFCD performed by local British Sub-Aqua Club diving enthusiasts 'Ydive' has annually monitored coral & marine life variety & density since 1997.
There are also the remnants of limekilns. There are total 4 limekilns in Hoi Ha Wan but only 2 remain comparatively intact. They are located on the eastern shore of inner Hoi Ha Wan. Limekiln industry was one of the oldest industries in Hong Kong, which refined lime from either oyster shells or coral skeletons for construction and agricultural uses. In the processes, limestone, i.e. calcium carbonate, in the shells and corals would be transformed into calcium oxide by means of heating.
It can be reached by taking Route 7 of of New Territories at Sai Kung Town Centre. The minibus provides service at daytime everyday, and the fare is 10 as of 2007.