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Map of The Grotto
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The Grotto

Northern Mariana IslandsDirections
Rash guard or 2mm shorty typical

The Grotto at a glance

The Grotto is a dive site in Northern Mariana Islands. Typically most favorable Aug · from 3 years of archive data. Recent reports put the water around 29°C (84°F). Check the latest conditions and entry details before you go.

Next window today· 16:00–18:00 · moderate · sunset 17:52

Forecast for this hour · 11:00 · run 19 h ago
2.0 m (6.5 ft)waves — about two meters expected (waves — about seven feet expected)

Tap a factor for its source and model point · Forecast 29°C · seasonal avg 30°C ( · Forecast 84°F · seasonal avg 85°F)

Dive windows this week

Lightest wind: Wed
Fri16:00–18:00 moderate

1.9 m waves · 12 kn wind (6.3 ft waves · 12 kn wind)

Sat7:00–9:00 moderate, 11:00–18:00 moderate

1.9 m waves · 10 kn wind (6.2 ft waves · 10 kn wind)

Sun7:00–18:00 moderate

1.6 m waves · 10 kn wind (5.3 ft waves · 10 kn wind)

Mon7:00–9:00 moderate, 15:00–18:00 moderate

1.7 m waves · 12 kn wind (5.5 ft waves · 12 kn wind)

Tue7:00–17:00 moderate, 17:00–18:00 favorable

1.6 m waves · 8 kn wind (5.2 ft waves · 8 kn wind)

Wed7:00–18:00 favorable

1.4 m waves · 5 kn wind (4.7 ft waves · 5 kn wind)

ThuNot in the forecast yet

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 5:48 · Sunrise 6:10 · Sunset 17:52 · some windows run past sunset

Source: Open-Meteo marine · model point 4.5 km from site · updated 22 Oct, 15:20 GMT+10

Forecast only — always assess conditions on site.

Compare this weekend’s windows near The Grotto

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?

Best months, historically

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

  1. January, 0% of days have historically been favorable, water has typically been 28°C (83°F), waves have typically been 2.7 m (9.0 ft), wind has typically been 19 knots
  2. February, 0% of days have historically been favorable, water has typically been 28°C (82°F), waves have typically been 2.8 m (9.1 ft), wind has typically been 20 knots
  3. March, 2% of days have historically been favorable, water has typically been 28°C (82°F), waves have typically been 2.4 m (8.0 ft), wind has typically been 17 knots
  4. April, 16% of days have historically been favorable, water has typically been 28°C (83°F), waves have typically been 2.0 m (6.7 ft), wind has typically been 16 knots
  5. May, 31% of days have historically been favorable, water has typically been 29°C (84°F), waves have typically been 1.9 m (6.2 ft), wind has typically been 15 knots
  6. June, 44% of days have historically been favorable, water has typically been 29°C (85°F), waves have typically been 1.6 m (5.1 ft), wind has typically been 15 knots
  7. July, 46% of days have historically been favorable, water has typically been 30°C (85°F), waves have typically been 1.7 m (5.6 ft), wind has typically been 15 knots
  8. August, 51% of days have historically been favorable, water has typically been 30°C (86°F), waves have typically been 1.6 m (5.3 ft), wind has typically been 14 knots, historically most favorable
  9. September, 46% of days have historically been favorable, water has typically been 30°C (86°F), waves have typically been 1.7 m (5.6 ft), wind has typically been 16 knots
  10. October, 19% of days have historically been favorable, water has typically been 30°C (85°F), waves have typically been 2.1 m (7.0 ft), wind has typically been 17 knots
  11. November, 3% of days have historically been favorable, water has typically been 29°C (85°F), waves have typically been 2.3 m (7.4 ft), wind has typically been 18 knots
  12. December, 0% of days have historically been favorable, water has typically been 29°C (84°F), waves have typically been 2.6 m (8.5 ft), wind has typically been 19 knots

August has 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 recorded at this site, by month

Recorded observations — evidence of past sightings, not a promise of what you’ll encounter.

  • Carangoides orthogrammus recorded here Mar (1 record)

    most recent 2018

  • Green Turtle recorded here Mar (1 record)

    Chelonia mydasmost recent 2018

Newest record here: 2018. Counts are occurrence records near this site from public biodiversity datasets (GBIF), grouped by calendar month across all sampled years. Sightings vary — past records are context, not a prediction.

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

No description for this site yet — divers who know it can suggest one below.

caveshorewall

No hazards recorded for this site yet — that never means there are none. Ask a local operator before you dive.

Reviews

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