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.

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.

Pot Rocks is a freshwater canyon site located within the Maryland-Virginia Quarries. The site is defined by geological formations where the river has carved deep pots or holes into the bedrock. These underwater rock formations create a distinct topography for snorkellers to explore. The site is suitable for advanced snorkellers due to the presence of moderate currents and cold water conditions. Depths at this location range between 1 and 5 metres. Access to the water is via the shore, and parking facilities are available nearby for visitors.

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.

Hyde's Quarry is a freshwater site featuring artificial reef structures and wrecks. Divers access the water from the shore to explore depths ranging from 1 to 24 metres, with an average depth of 15 metres. Visibility typically spans 5 to 9 metres. The site presents hazards including cold water, entanglement risks, and overhead environments within the wrecks. A thermocline is present at 15 to 20 feet deep during August, and bottom temperatures can reach 5 to 6 degrees Celsius. Facilities available at the location include changing rooms, air fills, parking, and guided tours. Night diving is permitted at this site.

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.