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Map of White Horse Beach (Flag Rock)
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Shore entry

White Horse Beach (Flag Rock)

Massachusetts, United StatesDirections
Open Water suggested2–9 m (5–30 ft) depthShore entry7mm or semi-dry + hood typical

White Horse Beach (Flag Rock) at a glance

White Horse Beach (Flag Rock) is a shore dive site in Massachusetts, United States with depths of 1.5–9.1 m (5–30 ft). Typically most favorable Jul–Aug · from 3 years of archive data. Divers commonly see Striped bass, Northern sea star, and Rock crab. Recent reports put the water around 14°C (57°F). Check the latest conditions and entry details before you go.

No window today· next: tomorrow 8:00–18:00 · favorable & moderate

Forecast for this hour · 18:00 · run 4 h ago
0.2 m (0.7 ft)waves — under half a meter expected (waves — under a foot expected)

Tap a factor for its source and model point · Forecast 14°C · seasonal avg 16°C ( · Forecast 57°F · seasonal avg 60°F)

Site hazards: Shallow rocky bottom around Flag Rock with surge on onshore (easterly) winds; cold water; summer swimmers; very limited legal parking in season.

Read the full hazards ↓

Dive windows this week

Smallest waves: Sun
MonNo window

0.2 m waves · 6 kn wind (0.8 ft waves · 6 kn wind)

Tue8:00–15:00 moderate, 15:00–18:00 favorable

0.8 m waves · 8 kn wind (2.6 ft waves · 8 kn wind)

Wed8:00–18:00 favorable

0.3 m waves · 5 kn wind (0.8 ft waves · 5 kn wind)

Thu8:00–17:00 favorable, 17:00–18:00 moderate

0.2 m waves · 12 kn wind (0.8 ft waves · 12 kn wind)

Fri8:00–9:00 moderate, 9:00–18:00 favorable

0.2 m waves · 11 kn wind (0.5 ft waves · 11 kn wind)

Sat8:00–18:00 favorable

0.2 m waves · 10 kn wind (0.7 ft waves · 10 kn wind)

Sun8:00–18:00 favorable

0.1 m waves · 9 kn wind (0.3 ft waves · 9 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 6:39 · Sunrise 7:07 · Sunset 17:44 · some windows run past sunset

Source: Open-Meteo marine · model point 12 km from site · updated 26 Oct, 13:29 GMT-4

Forecast only — always assess conditions on site.

Compare this weekend’s windows near White Horse Beach (Flag Rock)

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: Northern sea star, Rock crab, Hermit crab
Best time: At or near high tide (maximum depth ~30-35 ft only on the highest tides); calm days without onshore easterly wind; off-season for easy parking. Locally regarded as a good beginner or shakeout dive.

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, 84% of days have historically been favorable, water has typically been 5°C (41°F), waves have typically been 0.9 m (2.9 ft), wind has typically been 14 knots
  2. February, 82% of days have historically been favorable, water has typically been 4°C (39°F), waves have typically been 0.9 m (2.8 ft), wind has typically been 14 knots
  3. March, 81% of days have historically been favorable, water has typically been 4°C (40°F), waves have typically been 0.9 m (3.0 ft), wind has typically been 14 knots
  4. April, 92% of days have historically been favorable, water has typically been 7°C (44°F), waves have typically been 0.7 m (2.2 ft), wind has typically been 13 knots
  5. May, 96% of days have historically been favorable, water has typically been 11°C (53°F), waves have typically been 0.6 m (2.0 ft), wind has typically been 12 knots
  6. June, 96% of days have historically been favorable, water has typically been 16°C (61°F), waves have typically been 0.4 m (1.3 ft), wind has typically been 11 knots
  7. July, 100% of days have historically been favorable, water has typically been 18°C (64°F), waves have typically been 0.4 m (1.1 ft), wind has typically been 11 knots, historically most favorable
  8. August, 100% of days have historically been favorable, water has typically been 19°C (66°F), waves have typically been 0.4 m (1.3 ft), wind has typically been 10 knots, historically most favorable
  9. September, 93% of days have historically been favorable, water has typically been 19°C (66°F), waves have typically been 0.5 m (1.8 ft), wind has typically been 10 knots
  10. October, 90% of days have historically been favorable, water has typically been 16°C (60°F), waves have typically been 0.7 m (2.3 ft), wind has typically been 11 knots
  11. November, 90% of days have historically been favorable, water has typically been 11°C (53°F), waves have typically been 0.7 m (2.4 ft), wind has typically been 13 knots
  12. December, 88% of days have historically been favorable, water has typically been 8°C (46°F), waves have typically been 0.8 m (2.5 ft), wind has typically been 13 knots

July and August 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

White Horse Beach in the Manomet section of Plymouth is a shallow Cape Cod Bay shore dive centered on Flag Rock, the landmark boulder at the north end of the beach that has carried a painted American flag since 1941. The rocky bottom around the rock holds lobsters and typical New England bay life in roughly 10-30 ft of water - about 35 ft is possible only on the highest tides - making it a good beginner or cobweb-shakeout dive. Average visibility runs around 16-20 ft. Summer parking is the main challenge, with resident restrictions near the beach.

reefshore

Shallow rocky bottom around Flag Rock with surge on onshore (easterly) winds; cold water; summer swimmers; very limited legal parking in season.

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