Olowalu is located on the eroded west flank of the volcano that originally formed west Maui. Inland, the terrain is mountainous forest reserve. The watershed consists of the large Olowalu valley which has steep walls and is drained by Olowalu stream. The lower areas of the valley have a more moderate slope and were in sugar cane production until recently. A narrow coastal plain is occupied by the main road connecting West Maui with the rest of the island. A narrow basalt rampart separates the narrow olivine sand beach and the adjacent highway. Sections of the shoreline adjacent to the road are undergoing erosion. The subtidal consists of basalt cobble. A reef platform extends seaward with extensive sand channels interspersed with large aggregated coral formations. These large structures may be the result of reef accretion or may be volcanic covered with a veneer of limestone. Offshore topography is quite varied and complex with high relief.

The Olowalu beach contains some of the most extensive "spur and groove" reef formations seen on Maui. Coral cover is moderate to high (30-40%) in deeper water with substantial relief above the sand channels. Sand in the area is a mixture of carbonate (Halimeda fragments) and terrigenous sediments (high olivine content). At 4 m depth large heads of the coral Porites lobata are found. Numerous dead coral heads are found throughout the area and appear to be killed by resuspended sediments during high wave conditions. Live colonies also abound. The carbonate substrata and dead corals have an unusual dark appearance due to a thin coating of fine black basaltic sediment. The area is characterized by high coral diversity, moderate coral cover, complex bottom relief with varied reef formations. Coral coverage increases seaward.

The steep mountainous valley of Olowalu is in forest reserve (West Maui Natural Reserve Area and West Maui Forest Reserve. The lower portion of the Olowalu watershed was formerly used for sugar cane production. The fields have been taken out of production with the closing of the mills, and recently have been lying follow (2000). These may go into diversified agriculture, but areas at the north end of Olowalu are already under consideration for housing development.

Olowalu can be easily reached from the road. Consequently, this is a popular site for tourists and residents alike. The site is also accessible by boat. Parking is limited and there are no public facilities, so the area is only lightly used for recreational skin diving. Creel surveys during June and July of 1987 showed light fishing activity.