Cancellation reference
A line that cancels an earlier warning by its number, such as CANCEL HYDROLANT 1085/12.
When a new message replaces or ends an earlier one, it names it: "CANCEL HYDROLANT 1085/12." This is how a danger that is still being reported gets updated — the new text carries the latest position or description, and the old one is withdrawn in the same broadcast.
Chains of cancellations are how seahazards links reports over time on warning pages. A cancellation ends a message; by itself it does not say the danger was removed — a drifting object may simply have stopped being reported.
What the archive shows
58,326 messages in this archive use “Cancellation reference”, the earliest issued 1981-12-04 and the latest 2026-09-23. 56 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 2017, with 3,413 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 30,938 of 58,326 recorded messages (53%), the largest warning type group in this selection.
Located messages that use it fall in 92 sea areas; the most frequent are South Atlantic Ocean (3,577), North Pacific Ocean (2,674) and North Atlantic Ocean (2,631).
Its use is spread fairly evenly through the year: the busiest month, January, has 5,106 messages and the quietest, June, 4,565.
By warning series: HYDROLANT 23,650, HYDROPAC 23,471, NAVAREA IV 5,227 and NAVAREA XII 4,783, and 4 more.
Messages using it, by year of issue
By month of issue, all years
Where it appears · 92 sea areas
- South Atlantic Ocean 3,577
- North Pacific Ocean 2,674
- North Atlantic Ocean 2,631
- North Sea 1,344
- South Pacific Ocean 870
- South China Sea 822
- Celtic Sea 757
- Indian Ocean 752
- Mediterranean Sea - Eastern Basin 703
- Arabian Sea 661
- English Channel 511
- Bay of Bengal 453
In force now · 56
- HYDROLANT 1850/26 · Surveys · South Atlantic Ocean2026-09-18 · in force
…UNTIL 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 → - NAVAREA XII 639/26 · Surveys · Bering Sea2026-09-17 · in force
…AT DEPTH 15 METERS, ESTABLISHED IN: A. 65-46.86N 168-34.06W. B. 65-44.75N 168-15.76W. 2. CANCEL NAVAREA XII 422/25.
Scientific moorings, at depth 15 meters, established in: a. 65-46.86N 168-34.06W → - HYDROPAC 2700/26 · Surveys · Bering Sea2026-09-17 · in force
…1. SCIENTIFIC MOORING, AT DEPTH SEVEN METERS, ESTABLISHED IN 66-19.59N 168-57.01W. 2. CANCEL HYDROPAC 1795/25.
Scientific mooring, at depth seven meters, established in 66-19.59N 168-57.01W → - NAVAREA IV 898/26 · Surveys · Caribbean Sea2026-09-17 · in force
…RESOLUTION A.1023(26), PARAGRAPH 11.5.1, CONTACT NAVSAFETY@NGA.MIL SUBJ: MODU REPORT. 3. CANCEL NAVAREA IV 872/26.
NAVAREA IV mobile offshore drilling units positions at 171600Z sep: a. agosto 12 19-23.0N 092-03.1W → - NAVAREA III 139/26 · Surveys · Black Sea2026-09-12 · in force
…N - 031 15.53 E 10 NM. WIDE BERTH REQUESTED. 2. CANCEL THIS MESSAGE 192059Z OCT 26. 3.- CANCEL NAVAREA III 0121/26 AND THIS PARAGRAPH.
1- drilling operations by yildirim rig (imo 9705469, mmsi 271053959), supported by ertugrul bey, aybuke,… → - NAVAREA III 132/26 · Surveys · Black Sea2026-09-03 · in force
…42-10.43N 030-10.91E 10 MN BERTH REQUESTED CANCEL THIS PARAGRAPH 232359 UTC MAR 27. 2.- CANCEL NAVAREA III 0105/26 AND THIS PARAGRAPH.
Drilling operations by fatih platform (imo 9503770 →
How it reads in recent messages
- NAVAREA XII 657/26 · Missiles2026-09-23
…170-10.00E, 28-28.00N 164-59.00E, 26-39.00N 156-15.00E, 23-28.00N 144-48.00E. 2. CANCEL NAVAREA XII 655/26. 3. CANCEL THIS MSG 041933Z OCT 26.
Hazardous operations, space debris 1427Z to 1833Z daily 28 sep thru 04 oct in area bound by 23-55.00N… → - HYDROPAC 2761/26 · Missiles2026-09-23
…170-10.00E, 28-28.00N 164-59.00E, 26-39.00N 156-15.00E, 23-28.00N 144-48.00E. 2. CANCEL HYDROPAC 2749/26. 3. CANCEL THIS MSG 041933Z OCT 26.
Hazardous operations, space debris 1427Z to 1833Z daily 28 sep thru 04 oct in area bound by 23-55.00N… → - NAVAREA XII 654/26 · Nav aids · Gulf of Alaska2026-09-22
…HF AND MF TRANSMIT CAPABILITIES UNRELIABLE 1600Z TO 0030Z DAILY 23 THRU 25 SEP. 2. CANCEL NAVAREA XII 259/25. 3. CANCEL THIS MSG 250130Z SEP 26.
Uscg remote communication facility kodiak 57-46.00N 152-34.00W hf and mf transmit capabilities unreliable… → - HYDROPAC 2746/26 · Exercises · Bay of Bengal2026-09-22
…080-46.00E, 12-59.00N 080-46.00E, 12-59.00N 081-26.00E, 12-49.00N 081-26.00E. 2. CANCEL HYDROPAC 2732/26. 3. CANCEL THIS MSG 301230Z SEP 26.
Hazardous operations 0130Z to 1130Z daily 24 thru 30 sep in area bound by 12-49.00N 080-46.00E, 12-59.00N… → - HYDROPAC 2743/26 · Surveys · Arabian Sea2026-09-22
…072-19.25E, 18-29.63N 072-19.12E, 18-29.78N 072-10.39E. WIDE BERTH REQUESTED. 2. CANCEL HYDROPAC 2677/26. 3. CANCEL THIS MSG 160001Z OCT 26.
Survey operations in progress by kohinoor 1 until 12 oct, and M/V fugro mapper until 15 oct in areas bounded… → - HYDROPAC 2741/26 · Surveys · Indian Ocean2026-09-22
…115-42.52E, 20-35.47S 115-43.80E, 20-19.72S 115-43.80E. TWO MILE BERTH REQUESTED. 2. CANCEL HYDROPAC 2373/26.
Underwater operations in progress until further notice by M/V fugro kwilena in area bound by 20-19.72S… → - 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… → - HYDROPAC 2736/26 · Nav aids · Arafura Sea2026-09-22
GULF OF CARPENTARIA. AUSTRALIA. 1. DUYFKEN POINT LIGHT IN 12-34.15S 141-35.98E UNLIT. 2. CANCEL HYDROPAC 2725/26.
Duyfken point light in 12-34.15S 141-35.98E unlit →
Earliest in the archive
- HYDROLANT 1893/81 · Other1981-12-04
…NORTHERN BOUNDARY OF GUINEAS CLAIMED FISHING JURISDICTION HAS RECENTLY BEEN DISPUTED. 2. CANCEL HYDROLANT 874/77(51) AND THIS PARAGRAPH UPON RECEIPT.
Mariners are cautioned that the government of guinea is particularly sensitive to unauthorized fishing… →
Often in the same message
Related terms
- CANCEL THIS MSG
- The warning's own expiry: a line telling the reader when the message cancels itself.
- In force
- Currently valid: broadcast and not yet cancelled.
- NAVAREA
- One of the 21 ocean areas of the World-Wide Navigational Warning Service, each with a coordinator that broadcasts long-range warnings.
- HYDROLANT
- The U.S. long-range warning series for Atlantic waters outside NAVAREA IV, including the eastern Atlantic, the Mediterranean and adjoining seas.
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.