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Map of Halfmoon River
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Boat entry

Halfmoon River

South Carolina, United States
Open Water suggestedLong boat rides are the dominant logistical hazard3 m (9 ft) depthBoat entry5mm wetsuit typical

Boat dive — see Entry & access.

Halfmoon River at a glance

Halfmoon River is a boat dive site in South Carolina, United States with depths of up to 2.7 m (9 ft). Typically most favorable Jul · from 3 years of archive data. Divers commonly see Greater amberjack, Sand tiger shark, and Great barracuda. Recent reports put the water around 21°C (69°F). Check the latest conditions and entry details before you go.

Moderate window now· until 10:00, then favorable until 19:00 · sunset 18:39

Forecast for this hour · 9:00 · run 8 h ago
1.7 m (5.6 ft)waves — about a meter and a half expected (waves — about six feet expected)

Tap a factor for its source and model point · Forecast 21°C · seasonal avg 23°C ( · Forecast 69°F · seasonal avg 73°F)

Site hazards: Long boat rides are the dominant logistical hazard

Read the full hazards ↓

Dive windows this week

Lightest wind: Fri
Mon8:00–10:00 moderate, 10:00–19:00 favorable

1.7 m waves · 11 kn wind (5.4 ft waves · 11 kn wind)

Tue8:00–19:00 favorable

1.4 m waves · 11 kn wind (4.5 ft waves · 11 kn wind)

Wed8:00–19:00 favorable

1.5 m waves · 8 kn wind (5.0 ft waves · 8 kn wind)

Thu8:00–19:00 favorable

1.4 m waves · 11 kn wind (4.7 ft waves · 11 kn wind)

Fri8:00–19:00 favorable

1.1 m waves · 7 kn wind (3.6 ft waves · 7 kn wind)

Sat8:00–19:00 favorable

0.9 m waves · 10 kn wind (3.1 ft waves · 10 kn wind)

Sun8:00–19:00 favorable

0.9 m waves · 11 kn wind (2.9 ft waves · 11 kn wind)

Favorable windowModerate window— no window

Every forecast dive window each day, site-local time, from wave and wind forecasts. Numbers under each bar are daylight averages.

First light 7:10 · Sunrise 7:35 · Sunset 18:39 · some windows run past sunset

Source: Open-Meteo marine · model point 14 km from site · updated 26 Oct, 01:24 GMT-4

Forecast only — always assess conditions on site.

Compare this weekend’s windows near Halfmoon River

Forecast · NOAA tide model

Tide & slack timing

Loading tide predictions

Recent diver reports

Dated firsthand observations from divers — not current conditions.

No diver reports for this site yet. — one dated observation helps every diver after you.

Dived here today — did the forecast match?

What Divers Say

Known for: Greater amberjack, Great barracuda, Atlantic spadefish
Best time: May through October is the prime window for both SC and GA (SCDNR cites May-Oct as the most popular diving months; Charleston operators cite late spring to early fall, best May-Oct). Gray's Reef is dived year-round but most commonly April-November, with visibility often peaking in the coldest months and early summer. Surface water temps run roughly low-to-mid 80s F in summer down to low 50s F in winter (SCDNR: mid-80s summer / low 50s winter); offshore water peaks in the upper 70s-low 80s from June on.

Based on community reviews and site data. Conditions vary — always verify before diving.

Best months, historically

What conditions have historically been typical at this site, month by month — not a forecast.

  1. January, 96% of days have historically been favorable, water has typically been 12°C (53°F), waves have typically been 0.5 m (1.5 ft), wind has typically been 12 knots
  2. February, 94% of days have historically been favorable, water has typically been 14°C (56°F), waves have typically been 0.5 m (1.7 ft), wind has typically been 12 knots
  3. March, 95% of days have historically been favorable, water has typically been 17°C (62°F), waves have typically been 0.5 m (1.7 ft), wind has typically been 13 knots
  4. April, 94% of days have historically been favorable, water has typically been 21°C (70°F), waves have typically been 0.5 m (1.7 ft), wind has typically been 13 knots
  5. May, 98% of days have historically been favorable, water has typically been 25°C (77°F), waves have typically been 0.5 m (1.6 ft), wind has typically been 13 knots
  6. June, 99% of days have historically been favorable, water has typically been 28°C (82°F), waves have typically been 0.5 m (1.6 ft), wind has typically been 12 knots
  7. July, 100% of days have historically been favorable, water has typically been 30°C (86°F), waves have typically been 0.4 m (1.4 ft), wind has typically been 11 knots, historically most favorable
  8. August, 94% of days have historically been favorable, water has typically been 30°C (85°F), waves have typically been 0.5 m (1.7 ft), wind has typically been 12 knots
  9. September, 99% of days have historically been favorable, water has typically been 27°C (81°F), waves have typically been 0.6 m (2.0 ft), wind has typically been 12 knots
  10. October, 97% of days have historically been favorable, water has typically been 23°C (73°F), waves have typically been 0.6 m (2.0 ft), wind has typically been 11 knots
  11. November, 100% of days have historically been favorable, water has typically been 19°C (67°F), waves have typically been 0.5 m (1.6 ft), wind has typically been 11 knots, historically most favorable
  12. December, 98% of days have historically been favorable, water has typically been 14°C (58°F), waves have typically been 0.6 m (1.8 ft), wind has typically been 11 knots

July and November have typically had the largest share of favorable days here. Conditions vary year to year — this is historical context, not a forecast.

Based on 3 years of archive data. Bar height shows the share of days each month whose conditions have historically scored favorably.

Marine life seen at this site

Species noted at this site — not a promise of what you’ll encounter.

Species seen here

Rough labels: “Commonly seen” usually means two or more recorded sightings near this site in public dive logs (GBIF), “Occasionally seen” one; “Seasonal” and “Rarely seen” come from dive-guide research. Not a measured rate.

Fills & rentals nearby

No dive shops mapped within 25 km (16 mi). Know one? Add it to the map.

Data updated July 2026

Site details

Halfmoon River is a dive site in United States. Maximum depth is around 3 m. The site is reached by boat.

reef

Long boat rides are the dominant logistical hazard — most SC offshore wrecks lie 20-30+ nm offshore (some sites up to ~35 miles / SCDNR), translating to 2.5-3 hour transits to deeper wrecks like the Hebe off Murrells Inlet; GA reefs are generally closer (6-23 nm, with SAV ~6 nm off Tybee and KC ~9 mi off Wassaw), though deepwater experimental reefs sit 50-70 nm out. Visibility is highly variable and weather/tide-dependent: inshore and nearshore water can be murky (Charleston harbor and inshore reefs frequently 10-30 ft, occasionally measured in inches in the Cooper River), while offshore sites average 40-60 ft and can exceed 80 ft when Gulf Stream water spins inshore; Gray's Reef ranges from as little as 2 ft to ~65 ft. Current is a real concern — Gulf Stream influence and tidal flow drive drift conditions (drift diving is the recommended/required technique at Gray's Reef since anchoring is prohibited). Other hazards: entanglement in monofilament fishing line and lost rigging on these heavily fished structures; summer thunderstorms that build quickly offshore; cooler thermoclines at depth; and the offshore exposure itself (sea state can change during the long run back). Reef marker/nun buoys are not to be tied to (federal penalties in SC), and boaters risk fouling anchors on structure.

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