Sweeper Cove serves as the main harbour area of Adak, featuring industrial remnants that function as artificial reef structures. This site is suited for advanced divers due to the cold water temperatures ranging from 3C to 6C and moderate currents. Depths at the site vary between 11 and 40 metres. Access is available via both shore and boat entry. Divers and snorkellers should remain aware of boat traffic in the area. The habitat supports a variety of temperate marine life, including various fish and invertebrates typical of the region. Due to the challenging conditions and cold water, proper thermal protection is essential for all activities.

Clam Lagoon is a shallow, brackish body of water located on the north end of Adak Island in the United States. This site remains ice-free throughout the year, providing a rare opportunity for surface-level observation in the region. Snorkellers should be aware that conditions can be challenging, with moderate currents and surf present. Due to the nature of the environment and the potential for strong currents, this site is best suited for intermediate-level snorkellers. Water temperatures are cold, ranging from 4°C to 9°C depending on the month. Access to the water is via the shore.