HYDROLANT
The U.S. long-range warning series for Atlantic waters outside NAVAREA IV, including the eastern Atlantic, the Mediterranean and adjoining seas.
HYDROLANT warnings are issued by the U.S. National Geospatial-Intelligence Agency (NGA) for Atlantic waters beyond the NAVAREA the United States coordinates itself. Many repeat, in NGA's standard wording, dangers first broadcast by the coordinator responsible for that area — so a HYDROLANT about the English Channel or the eastern Mediterranean often has a British, French or other national warning behind it.
Each message carries a number and two-digit year, such as HYDROLANT 1159/12. NGA's archive of cancelled HYDROLANTs is one of the sources this site's history is built from.
What the archive shows
23,742 messages in this archive use “HYDROLANT”, the earliest issued 1948-05-27 and the latest 2026-09-22. 10 of them are in force in the latest lists we collected. A hazard reported again and again counts once per message.
The largest yearly count is 2000, with 1,469 messages. Collection is incomplete between 2024-05 and 2026-08-17, so 2024, 2025 and 2026 are not comparable with fully collected years.
Other accounts for 11,814 of 23,742 recorded messages (50%), the largest warning type group in this selection.
Located messages that use it fall in 46 sea areas; the most frequent are South Atlantic Ocean (3,506), North Sea (1,339) and North Atlantic Ocean (1,322).
Its use is spread fairly evenly through the year: the busiest month, January, has 2,204 messages and the quietest, September, 1,856.
By warning series: HYDROLANT 23,669, HYDROPAC 58, NAVAREA IV 8 and NAVAREA XII 4, and 2 more.
Messages using it, by year of issue
By month of issue, all years
Where it appears · 46 sea areas
- South Atlantic Ocean 3,506
- North Sea 1,339
- North Atlantic Ocean 1,322
- Celtic Sea 759
- Mediterranean Sea - Eastern Basin 701
- English Channel 512
- Black Sea 368
- Irish Sea and St. George's Channel 286
- Inner Seas off the West Coast of Scotland 234
- Mediterranean Sea - Western Basin 209
- Tyrrhenian Sea 142
- Aegean Sea 136
In force now · 10
- HYDROLANT 1850/26 · Surveys · South Atlantic Ocean2026-09-18 · in force
…250259Z SEP BY M/V SIEM PILOT IN 22-25.32S 039-56.55W. WIDE BERTH REQUESTED. 2. CANCEL HYDROLANT 1844/26. 3. CANCEL THIS MSG 250400Z SEP 26.
Underwater operations in progress until 250259Z sep by M/V siem pilot in 22-25.32S 039-56.55W → - HYDROLANT 1457/26 · Exercises · South Atlantic Ocean2026-07-29 · in force
…24-38.07S 042-29.30W, 24-38.97S 042-28.27W. TWO MILE BERTH REQUESTED. 2. CANCEL HYDROLANT 1456/26. 3. CANCEL THIS MSG 060500Z JUN 27.
Hazardous operations in progress until 060400Z jun 27 in area bound by 24-39.87S 042-29.30W, 24-39.78S… → - HYDROLANT 1160/26 · Surveys · South Atlantic Ocean2026-06-17 · in force
…040-20.52W, 22-59.46S 042-00.84W, 25-55.32S 040-11.58W. WIDE BERTH REQUESTED. 2. CANCEL HYDROLANT 1157/26. 3. CANCEL THIS MSG 150001Z NOV 26.
Underwater operations in progress until 140001Z nov by M/V fugro vaquita in area bound by 22-03.00S… → - HYDROLANT 657/26 · Nav aids · South Atlantic Ocean2026-04-02 · in force
…1. RACON AT CABO SAO TOME LIGHT 22-02.52S 041-03.17W OFF AIR UNTIL 28 SEP. 2. CANCEL HYDROLANT 1667/25. 3. CANCEL THIS MSG 290001Z SEP 26.
RACON at cabo sao tome light 22-02.52S 041-03.17W off air until 28 sep → - HYDROLANT 638/26 · Nav aids · South Atlantic Ocean2026-03-31 · in force
…BRAZIL. 1. PONTA DOS MEROS LIGHT 23-13.57S 044-20.83W UNLIT UNTIL 26 SEP. 2. CANCEL HYDROLANT 635/26. 3. CANCEL THIS MSG 270001Z SEP 26.
Ponta dos meros light 23-13.57S 044-20.83W unlit until 26 sep → - HYDROLANT 585/26 · Nav aids · North Atlantic Ocean2026-03-23 · in force
NORTH ATLANTIC. 1. PAP ODAS BUOY RELOCATED TO 48-56.30N 016-22.50W. 2. CANCEL HYDROLANT 579/26.
Pap odas buoy relocated to 48-56.30N 016-22.50W →
How it reads in recent messages
- HYDROLANT 1875/26 · Surveys · North Atlantic Ocean2026-09-22
…049-06.33W, 04-07.01N 049-23.23W, 04-15.75N 049-43.94W. WIDE BERTH REQUESTED. 2. CANCEL HYDROLANT 1825/26. 3. CANCEL THIS MSG 040001Z OCT 26.
Survey operations in progress until 03 oct by M/V amazon warrior, M/V venture g and M/V big john VII towing… → - HYDROLANT 1848/26 · Nav aids · Inner Seas off the West Coast of Scotland2026-09-17
…OF THE HEBRIDES. SCOTLAND. 1. DUBH ARTACH LIGHT 56-08.0N 006-38.1W UNRELIABLE. 2. CANCEL HYDROLANT 1847/26.
Dubh artach light 56-08.0N 006-38.1W unreliable → - HYDROLANT 1832/26 · Exercises · North Atlantic Ocean2026-09-15
…017-21.75W, 23-44.54N 017-19.04W, 23-52.58N 017-10.39W, 23-55.07N 017-00.00W. 2. HYDROLANT 1830/26. 3. CANCEL THIS MSG 180100Z SEP 26.
Hazardous operations 160001Z to 180001Z sep in areas bound by: a. 26-50.00N 014-00.00W, 26-50.00N… → - HYDROLANT 1825/26 · Surveys · North Atlantic Ocean2026-09-15
…049-06.33W, 04-07.01N 049-23.23W, 04-15.75N 049-43.94W. WIDE BERTH REQUESTED. 2. CANCEL HYDROLANT 1774/26. 3. CANCEL THIS MSG 270001Z SEP 26.
Survey operations in progress until 26 sep by M/V amazon warrior, M/V venture g and M/V big john VII towing… → - HYDROLANT 1820/26 · Surveys · South Atlantic Ocean2026-09-14
…ALTAIR SKY AND M/V COMANDO B IN 20-23.02S 040-09.23W. WIDE BERTH REQUESTED. 2. CANCEL HYDROLANT 1814/26. 3. CANCEL THIS MSG 281900Z SEP 26.
Underwater operations 0800Z to 1800Z daily until 25 sep by M/V altair sky and M/V comando b in 20-23.02S… → - HYDROLANT 1818/26 · Exercises · North Atlantic Ocean2026-09-14
…A. 27 MILES OF 57-27.50N 008-20.50W. B. 20 MILES OF 57-43.50N 008-58.80W. 2. CANCEL HYDROLANT 1811/26. 3. CANCEL THIS MSG 161800Z SEP 26.
Hazardous operations 160600Z to 161700Z sep in areas within: a. 27 miles of 57-27.50N 008-20.50W → - HYDROLANT 1803/26 · Missiles · South Atlantic Ocean2026-09-11
…034-01.81W, 06-03.44S 033-56.53W, 05-52.66S 034-03.34W, 05-49.30S 034-25.37W. 2. CANCEL HYDROLANT 1798/26. 3. CANCEL THIS MSG 192100Z SEP 26.
Hazardous operations, rocket launching 0800Z to 2000Z daily 15 thru 19 sep in area bound by 05-55.28S… →
Earliest in the archive
- SPECIAL 1/48 · Other1948-05-27
…NGA COMMENCED ISSUING WARNINGS AS NAVAREAS IV AND XII BROADCASTS IN ADDITION TO THE HYDROLANT AND HYDROPAC SERIES.
Navigational warnings broadcast by nga are normally divided into categories, hydrolants and hydropacs (1),… →
Often in the same message
Related terms
- NAVAREA
- One of the 21 ocean areas of the World-Wide Navigational Warning Service, each with a coordinator that broadcasts long-range warnings.
- HYDROPAC
- The U.S. long-range warning series for the Pacific outside NAVAREA XII and for the Indian Ocean, Persian Gulf and adjoining seas.
- HYDROARC
- The U.S. long-range warning series for the Arctic Ocean.
- Cancellation reference
- A line that cancels an earlier warning by its number, such as CANCEL HYDROLANT 1085/12.
Counts cover the messages in this archive that use the term, recounted 2026-09-24; see coverage for what is collected and since when. Not for navigation — follow official NAVAREA and coastal broadcasts.