As a result, inshore waters of the bay near the boat ramp area are usually very murky. The bottom here consists of small boulders and silt. Visibility improves as you swim farther out, or to the sides. The middle of the bay is a feature less sand channel, sloping gradually to a depth of about 60 feet at the bay's mouth. On either side of the bay are dense coral growths, in waters about 10 to 40 feet deep.
Coral is more abundant and diverse along the northeastern shoreline.
Small caves and archways are found near the point on the bay's left side. The bottom at Mokule'ia Bay is mostly sand. At the right point are large submerged boulders, and fingers of lava occur along the left point. Both points offer good coral growth. Depths range from about ten to fifty feet.