How deep is Port Jefferson/Mount Sinai?

Port Jefferson/Mount Sinai ranges from 26.8 to 28.7 metres deep (88–94 feet). It is a saltwater site rated as advanced difficulty. Depths vary across the site, so plan your profile to your training and verify conditions locally.

Is Port Jefferson/Mount Sinai a shore dive or a boat dive?

Port Jefferson/Mount Sinai is a boat dive — access is by boat rather than from shore. The entry area is recorded as moderately exposed to surge. No facilities are recorded at the site, and cell service is recorded as good. Entry details and parking notes, where known, are listed in the access section of this page.

Can beginners dive Port Jefferson/Mount Sinai?

Port Jefferson/Mount Sinai is rated as advanced difficulty, which may not suit new divers. Listed depths run from 26.8 to 28.7 metres (88–94 feet). Access is by boat. Consider your experience level, conditions, and local guidance before planning.

When is the best time to dive Port Jefferson/Mount Sinai?

Summer on slack tide; manage depth and bottom time. Weather-limited in winter. Conditions vary, so check the latest reports and forecasts on the dive site page before your trip.

What will I see at Port Jefferson/Mount Sinai?

Divers at Port Jefferson/Mount Sinai in United States commonly report sightings of Black sea bass, Cunner, Tautog (blackfish), Scup (porgy), and American lobster. Black sea bass, Cunner, Tautog (blackfish), and Scup (porgy) are recorded as common sightings, while American lobster is reported only occasionally. Marine life varies by season and conditions—check the site page for recent diver observations and photos.

What hazards are recorded at Port Jefferson/Mount Sinai?

Depth (~90 ft) and Long Island Sound current; cold/dark at depth; limited visibility; boat traffic; fishing tackle. Hazards and conditions change, so verify current local information before diving.

Add the first photo

AdvancedBoat entry

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 an 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, Cunner, and Tautog (blackfish). Recent reports put the water around 24°C (74°F). Check the latest conditions and entry details before you go.

Marine model · graded 14h ago

0.0 mwaves — under half a meter expected

Tap a factor for its source and model point · Forecast 24°C · seasonal avg 22°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: Sat

Fri7:00–20:00

Sat7:00–20:00

Sun7:00–20:00

Mon7:00–20:00

Tue7:00–20:00

Wed7:00–19:00

Thu7:00–19:00

Favorable windowModerate window— no window

First light 6:01 · Sunrise 6:29 · Sunset 19:08

Source: Open-Meteo marine · model point 6.9 km from site · graded 14h ago

Forecast only — always assess conditions on site.

Forecast · NOAA tide model

Tide & slack timing

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: Black sea bass, Cunner, Tautog (blackfish)

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.

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

Fills & rentals nearby

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

ORBIT22.3 km
Report a fix

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

Data updated June 2026

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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