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Alcatraz North Fog Signal Lighthouse

🇺🇸San Francisco, USOperational

Location & Light Range

About Alcatraz North Fog Signal Lighthouse

The Alcatraz North Fog Signal, built in 1900, is a single-story structure on the northwest end of Alcatraz Island. Painted white, the building is illuminated after dark. Initially equipped with a fog bell, it was updated to a siren in 1913, and subsequently fitted with a horn to enhance sound projection. The facility, which remains active, provides foghorn signals to alert mariners to the island's presence. It is situated 1.4 km from San Francisco.

Why it matters: This signal serves as a navigation aid for vessels entering San Francisco Bay, particularly on the island's northwest side when visibility is poor. Its consistent function assists in preventing collisions with the island.

Tower & Structure

Tower Color
white and floodlit at night

Structure: A 1-story building, painted white and floodlit at night.

Location

City
San Francisco
Country
🇺🇸United States
Region
California
Sea Region
northwestern tip of Alcatraz island
Latitude
37.8281°
Longitude
-122.4256°

Nearby Vessels

Flag
Type
Name
Dist.

Construction & History

Year Built
1900

Significant events: The fog bell was replaced by a siren in 1913, later replaced by a horn.

References & Identifiers

Nearest Port
San Francisco(1.4 km)
Admiralty No.
G4084
USCG No.
6-4325
ARLHS No.
USA-908
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Frequently Asked Questions

Which ports and harbors does Alcatraz North Fog Signal Lighthouse guide vessels into?+
Alcatraz North Fog Signal Lighthouse assists vessels approaching 5 nearby ports. The closest is TRAVIS at 2.4 NM to the W. Other ports served include TREASURE ISLAND (2.6 NM E), Sausalito (3 NM NW), Tiburon (3 NM NNW), San Francisco (3.5 NM SSE). Mariners should consult the relevant chart for full approach and pilotage information.
Is Alcatraz North Fog Signal Lighthouse still active and maintained?+
Yes, Alcatraz North Fog Signal Lighthouse is currently operational. It is actively maintained and continues to emit its characteristic light signal for marine navigation. Most modern lighthouses are automated and monitored remotely by the national maritime authority.
What shipping routes pass near Alcatraz North Fog Signal Lighthouse?+
Alcatraz North Fog Signal Lighthouse is located within the US West Coast shipping lane — a major trans-Pacific trade route serving West Coast ports of the United States. This makes it an important navigation reference for commercial shipping traffic in the region.
How can I track vessels near Alcatraz North Fog Signal Lighthouse?+
You can track vessels near Alcatraz North Fog Signal Lighthouse in real time using MarineRadar. The platform shows live AIS positions of ships in the area, including vessel name, type, flag, speed, and course. Use the "Track Vessels Nearby" button on this page to open the live map centered on this lighthouse.