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Port Jefferson/Mount Sinai

New York, United States
AOW suggested27–29 m depthBoat entry3mm wetsuit typical

Boat dive — see Entry & access.

Port Jefferson/Mount Sinai at a glance

Port Jefferson/Mount Sinai is a advanced boat dive site in New York, United States with depths of 26.8–28.7 m (88–94 ft). Typically most favorable May–Jul · from 3 years of archive data. Divers commonly see Black sea bass, Tautog (blackfish), and Scup (porgy). Recent reports put the water around 23°C (73°F). Check the latest conditions and entry details before you go.

Marine model · graded 4h ago
0.1 mwaves — under half a meter expected

Tap a factor for its source and model point · Forecast 23°C · seasonal avg 24°C

Site hazards: Depth (~90 ft) and Long Island Sound current; cold/dark at depth; limited visibility; boat traffic; fishing tackle.

Read the full hazards ↓

Dive windows this week

Best: Sun
Sun6:00–21:00
Mon6:00–21:00
Tue6:00–21:00
Wed6:00–21:00
Thu6:00–21:00
Fri6:00–21:00
Sat6:00–21:00

Favorable windowModerate window— no window

First light 5:11 · Sunrise 5:42 · Sunset 20:14

Source: Open-Meteo marine · model point 6.9 km from site · graded 4h ago

Forecast only — always assess conditions on site.

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.

What Divers Say

Known for: Black sea bass, Tautog (blackfish), Scup (porgy)
Best time: Summer on slack tide; manage depth and bottom time.

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. Jan94%5°C0.6 m
  2. Feb95%4°C0.5 m
  3. Mar91%5°C0.6 m
  4. Apr96%8°C0.5 m
  5. May100%13°C0.4 m
  6. Jun100%18°C0.3 m
  7. Jul100%24°C0.2 m
  8. Aug99%23°C0.3 m
  9. Sep98%22°C0.4 m
  10. Oct96%18°C0.5 m
  11. Nov93%14°C0.6 m
  12. Dec92%8°C0.6 m

May, June, and July havetypically 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

  • Black sea bassCommonly seen
  • Tautog (blackfish)Commonly seen
  • Scup (porgy)Commonly seen
  • American lobsterOccasionally seen
  • CunnerCommonly seen

Fills & rentals nearby

Facts from OpenStreetMap, corrected by the community — listed by distance only. Details change; confirm with the shop.

Shop facts come from OpenStreetMap and community corrections, shown nearest first. PickADive lists facts and contacts only — no listing is sponsored or ranked.

Site details

The Port Jefferson/Mount Sinai Reef is a 50-acre NYSDEC artificial reef in Long Island Sound about 1.79 nautical miles northeast of Port Jefferson Inlet, in 88-94 ft of water. Built from a barge and concrete buoy sinkers with concrete blocks added in 2025, it is a deep Sound reef best suited to advanced/deep divers. Black sea bass, tautog and scup hold on the structure; visibility is variable.

boatreef

Depth (~90 ft) and Long Island Sound current; cold/dark at depth; limited visibility; boat traffic; fishing tackle.

Reviews

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