Hobo Beach at York Road Access offers a freshwater snorkeling experience within the Maryland-Virginia Quarries region. The site features a grassy bank entry leading into a deep, slow-moving section of the river. Depths at this location range from 8 to 39 metres. Water temperatures remain consistently cold, between 45 and 50 degrees Fahrenheit, due to the release from the nearby Prettyboy Reservoir. The site is suitable for beginners, though the deep water and cold temperatures require appropriate thermal protection. Facilities at the access point include parking and toilets. Typical sessions last approximately 45 minutes, with mild currents present throughout the area.

Bunker Hill is a deep pool located within the Maryland-Virginia Quarries near Prettyboy Reservoir. This freshwater site features a slower river flow, which allows for observation of the riverbed. Snorkellers can expect mild currents, though the water remains cold year-round, typically ranging between 45-50°F due to reservoir releases. The site is suitable for beginners and offers shore access. While specific sightings are not confirmed, the habitat supports various temperate freshwater fish and invertebrates typical of the region. Facilities at the site include parking and toilets. Due to the consistently low water temperatures, appropriate thermal protection is necessary for all visitors.

Hemlock Gorge is a shallow snorkelling site located below the dam near Prettyboy Reservoir. The area consists of shallow riffles and small pools shaded by hemlock trees. With an average depth of one metre and a maximum depth of two metres, it is suitable for beginners. Entry is via the shore. Conditions vary, with visibility typically ranging between one and four metres and moderate currents present. Snorkellers should be aware of potential entanglement hazards in the water. A typical session lasts approximately 30 minutes.

Merryman's Trail Beach is a freshwater dive site located at the Maryland-Virginia Quarries near Loch Raven Reservoir. This artificial reef site features a sandy shoreline entry point situated just north of the Loch Raven Drive bridge. Divers should be aware of significant thermal stratification, with surface temperatures ranging from 4C to 19C and deeper water remaining consistently cold. Depths at this site extend to 73 metres. Due to the proximity to the main road and potential for boat traffic, divers must exercise caution. The site is suitable for beginners, though conditions vary and visibility can be low.

Loch Raven Cliffs is a quarry site in the United States offering depths ranging from 3 to 73 metres. Access is via shore, though the site is primarily suited for advanced divers due to challenging conditions including low visibility of 1 to 3 metres, entanglement risks, and down currents. The water temperature fluctuates between 4C and 28C, with significant thermal stratification occurring during summer months. Divers should be aware of boat traffic and the presence of a thermocline. Parking is available near the site. Snorkelling is not recommended here, as the site receives a rating of 1/5 for that activity.

Sinsheim Cove, located within Codorus State Park, serves as a designated area for underwater exploration. This freshwater site features submerged tree stumps and old foundations that create an artificial reef environment. Divers and snorkellers access the water from the shore. Conditions at the site include mild currents and visibility ranging from three metres upwards. Due to the presence of submerged structures, divers should be aware of potential entanglement risks and overhead environments. The site is suited for intermediate divers and offers a range of facilities including parking, toilets, showers, changing rooms, a rinse station, air fills, equipment rental, a cafe, first aid, a dive shop, boat charter, guided tours, and gear storage.

Guppy Gulch is a 15-acre freshwater reservoir and former slate quarry offering shore-entry diving and snorkelling. The site features various sunken objects, including trains and trucks, alongside floating docks and inflatable water parks. Depths range from 5 to 18 metres, with an average of 10 metres. Conditions include mild currents and visibility between 2 and 6 metres. Divers should be prepared for significant thermoclines and cold water at depth. The site is suitable for beginners and supports night diving, with typical dive durations of 45 minutes. The habitat supports temperate freshwater fish and invertebrates typical of the region.

Atlantic Coral Reef is an artificial reef exhibit located in the Maryland-Virginia Quarries. This controlled saltwater environment maintains a depth of 4 metres and offers a unique opportunity for divers to explore a contained habitat. The site is suitable for beginners, with shore entry and mild conditions. Divers can expect to encounter a variety of temperate marine life and invertebrates typical of the region. The dive typically lasts 40 minutes, with group sizes limited to six participants. Facilities at the site include parking and air fills. Divers should be aware of potential hazards, including entanglement, overhead environments, and sharp coral structures.