Sea Ledger, September 2023

2023-09-01 to 2023-09-30 · archive

issued: 720
warning-days in force: 13,438
in force at month end: 432
sea × type cells: 248

baseline: same month, previous 5 years (2022-09, 2021-09, 2020-09, 2019-09, 2018-09)

By type

type	issued	warning-days	in force at end
Exercises	205	1,518.6	43
Icebergs	98	118.5	4
Incidents	92	1,031.4	27
Surveys	65	2,191.5	78
Missiles	58	450	17
Nav aids	50	4,552.1	151
Quakes	38	109.2	5
Towing	28	27.4	0
Cable ops	27	638.2	19
Derelicts	19	159.1	3
Spills	9	190	2
Debris	9	84.3	2
Storms	8	13.3	0
Other	6	444.4	17
Wrecks	4	1,267.1	42
Mines	1	83.3	3
Restricted	1	65.7	2
Volcanic	1	251.8	9
Piracy	1	2.4	0
Structures	0	120	4
War risk	0	30	1
Ordnance	0	90	3

By sea and type · 200 cells, most issued first

cell	issued	warning-days	at end	longest d	vs 5 y
Exercises · North Pacific Ocean	41	312.7	8	64	1.8× / 23.4
Icebergs · Southern Ocean	33	37.4	1	32	1.1× / 29.2
Icebergs · South Atlantic Ocean	31	30.9	1	30	1.3× / 24
Icebergs · Labrador Sea	29	37	2	31	1.0× / 28.4
Towing · North Pacific Oceansurge	28	27.4	0	—	3.9× / 7.2
Exercises · Bay of Bengal	20	89.2	7	47	1.8× / 11.4
Surveys · South Atlantic Ocean	18	215	6	128	1.0× / 18.2
Missiles · Indian Oceansurge	18	134.8	5	37	5.6× / 3.2
Exercises · South Atlantic Ocean	18	131.7	2	45	1.4× / 13.2
Exercises · Arabian Sea	16	77.7	2	33	1.5× / 10.4
Missiles · North Atlantic Ocean	16	49.5	3	36	1.4× / 11
Exercises · Celtic Seasurge	15	15.3	0	—	4.7× / 3.2
Incidents · South China Sea	14	146.5	2	44	0.6× / 23.4
Quakes · South Pacific Ocean	13	37.9	1	25	1.1× / 12
Cable ops · North Atlantic Ocean	11	138	5	113	1.7× / 6.6
Nav aids · North Atlantic Oceanlong running	10	355.2	11	898	1.7× / 6
Exercises · South Pacific Ocean	10	52.2	1	26	0.8× / 12.6
Incidents · North Pacific Ocean	9	130.8	2	46	0.6× / 15.4
Nav aids · South Atlantic Oceanlong running	8	1,308.7	44	414	1.1× / 7
Incidents · North Atlantic Ocean	8	149.7	6	47	0.9× / 9
Incidents · Gulf of Mexicosurge	8	136.5	2	38	8.0× / 1
Exercises · Gulf of Mexicosurge	8	67.9	0	—	10× / 0.8
Exercises · Caribbean Seasurge	8	50.4	1	20	5.0× / 1.6
Quakes · North Pacific Ocean	8	23.3	1	27	1.5× / 5.2
Exercises · Andaman or Burma Seasurge	8	15.6	1	26	2.9× / 2.8
Incidents · Indian Ocean	8	9.7	0	—	1.4× / 5.6
Exercises · Black Sealong running	7	121.5	4	556	0.5× / 13.4
Incidents · South Pacific Ocean	7	80.4	3	47	1.5× / 4.8
Exercises · North Atlantic Ocean	7	71.3	3	37	0.8× / 9
Exercises · Laccadive Seasurge	7	47.4	1	32	2.3× / 3
Derelicts · North Atlantic Oceansurge	7	17.5	1	45	2.2× / 3.2
Exercises · Bay of Biscaysurge	7	17.3	1	22	3.2× / 2.2
Storms · North Atlantic Ocean	7	10.3	0	—	1.6× / 4.4
Incidents · Coral Sea	7	1.7	0	—	1.3× / 5.4
Surveys · South Pacific Oceansurge	6	156.2	7	193	5.0× / 1.2
Missiles · South Pacific Ocean	6	87.8	3	32	0.7× / 8.4
Exercises · Philippine Sea	6	27.8	0	—	0.9× / 6.8
Surveys · Baffin Baynew	6	26.9	1	26	new / 0
Nav aids · North Pacific Oceanlong running	5	187.5	7	542	1.1× / 4.4
Surveys · Arabian Sea	5	80.6	4	30	1.6× / 3.2
Incidents · Caribbean Sea	5	66.1	3	47	1.7× / 3
Incidents · South Atlantic Ocean	5	60	4	48	1.0× / 4.8
Missiles · Barentsz Sea	5	41.8	1	23	0.6× / 8
Exercises · Indian Oceansurge	5	26.2	0	—	8.3× / 0.6
Surveys · North Atlantic Ocean	4	236.3	11	272	0.7× / 5.8
Surveys · Gulf of Mexicosurge	4	121.9	4	153	20× / 0.2
Incidents · Arabian Sea	4	60.8	0	—	1.1× / 3.6
Missiles · North Pacific Ocean	4	60.7	3	214	0.5× / 8
Exercises · Tasman Seasurge	4	21.2	0	—	6.7× / 0.6
Debris · Indian Oceansurge	4	11.1	0	—	2.9× / 1.4
Nav aids · Gulf of Alaskasurge	4	10.6	0	—	20× / 0.2
Quakes · Indian Ocean	4	10	1	14	1.4× / 2.8
Surveys · Persian Gulflong running	3	185.7	6	506	0.6× / 5.4
Cable ops · Persian Gulfsurge	3	139.2	5	192	5.0× / 0.6
Surveys · Indian Ocean	3	137.7	4	218	1.7× / 1.8
Nav aids · North Sea	3	67.2	2	99	0.6× / 5.2
Cable ops · Arabian Seasurge	3	61.2	2	31	7.5× / 0.4
Surveys · North Sea	3	52.4	2	45	1.3× / 2.4
Nav aids · Celtic Seasurgelong running	3	37.6	2	407	3.8× / 0.8
Nav aids · Inner Seas off the West Coast of Scotland	3	34.2	2	43	1.7× / 1.8
Surveys · Bay of Bengal	3	33.5	2	61	1.3× / 2.4
Wrecks · Mediterranean Sea - Eastern Basinnew	3	28.3	2	14	new / 0
Exercises · Gulf of Californianew	3	24.9	0	—	new / 0
Incidents · Bay of Bengal	3	19.1	0	—	1.7× / 1.8
Icebergs · Laptev Seasurge	3	9	0	—	3.8× / 0.8
Debris · North Pacific Oceansurge	3	9	0	—	15× / 0.2
Missiles · Bay of Bengalsurge	3	8	0	—	15× / 0.2
Derelicts · Coral Seasurge	3	7.1	0	—	5.0× / 0.6
Spills · North Atlantic Oceanlong running	2	61	1	436	0.7× / 2.8
Surveys · Sea of Okhotsk	2	60.2	1	126	1.3× / 1.6
Exercises · Barentsz Sea	2	59.3	1	32	0.8× / 2.4
Spills · The Coastal Waters of Southeast Alaska and British Columbia	2	44	0	—	2.5× / 0.8
Spills · Gulf of Mexico	2	38	0	—	0.5× / 4.4
Spills · North Pacific Ocean	2	33	1	39	1.4× / 1.4
Exercises · Red Sea	2	22.6	1	23	3.3× / 0.6
Derelicts · Gulf of Mexico	2	21.4	0	—	3.3× / 0.6
Exercises · Chukchi Sea	2	19.8	0	—	3.3× / 0.6
Cable ops · Philippine Sea	2	11.5	0	—	5.0× / 0.4
Nav aids · Bristol Channel	2	10.8	0	—	5.0× / 0.4
Missiles · Norwegian Sea	2	9.9	0	—	5.0× / 0.4
Surveys · Barentsz Sea	2	9.8	1	17	2.5× / 0.8
Incidents · Philippine Sea	2	9.1	1	25	0.8× / 2.4
Quakes · Coral Sea	2	5.4	1	9	1.4× / 1.4
Quakes · Solomon Sea	2	5.2	1	16	5.0× / 0.4
Derelicts · North Pacific Ocean	2	5	0	—	2.0× / 1
Exercises · Coral Sea	2	3.4	2	2	3.3× / 0.6
Cable ops · Hudson Bay	2	3.2	0	—	3.3× / 0.6
Incidents · Banda Sea	2	1.7	0	—	2.0× / 1
Other · North Pacific Ocean	2	0.2	1	18	0.3× / 6
Nav aids · Caribbean Sealong running	1	828.3	27	956	0.3× / 3.6
Nav aids · South Pacific Oceanlong running	1	385	12	555	0.2× / 5.2
Volcanic · Philippine Sealong running	1	251.8	9	1,016	2.5× / 0.4
Nav aids · Gulf of Mexicolong running	1	241.3	8	911	1.0× / 1
Wrecks · The Northwestern Passageslong running	1	164.6	5	758	0.5× / 2.2
Nav aids · Coral Sea	1	100.4	4	160	0.2× / 4.6
Surveys · Arctic Oceanlong running	1	91.7	4	384	1.7× / 0.6
Nav aids · Arabian Sealong running	1	91	3	703	0.7× / 1.4
Other · Caribbean Sealong running	1	90.1	3	702	5.0× / 0.2
Mines · Black Sealong running	1	83.3	3	583	new / 0
Surveys · Chukchi Sea	1	81.3	3	52	new / 0
Nav aids · Persian Gulflong running	1	67.3	3	494	2.5× / 0.4
Nav aids · Indian Ocean	1	59.6	2	38	0.5× / 2
Surveys · Caribbean Sea	1	58.4	2	335	0.5× / 2
Cable ops · South Atlantic Ocean	1	49.1	2	99	0.6× / 1.8
Cable ops · South China Sea	1	47.9	1	115	0.7× / 1.4
Cable ops · North Pacific Ocean	1	45	1	71	0.6× / 1.6
Incidents · Mediterranean Sea - Eastern Basin	1	42.3	0	—	0.3× / 3.8
Surveys · Coral Sea	1	41	2	46	new / 0
Other · South Pacific Ocean	1	36.7	2	153	1.0× / 1
Exercises · Japan Sea	1	31.9	1	33	0.4× / 2.8
Nav aids · Andaman or Burma Sea	1	31.2	1	145	1.7× / 0.6
Surveys · Mediterranean Sea - Eastern Basin	1	30	1	30	0.3× / 3
Incidents · Mediterranean Sea - Western Basin	1	29.7	0	—	1.3× / 0.8
Nav aids · Gulf of Bothnia	1	24.6	1	24	new / 0
Incidents · Great Australian Bight	1	14.8	0	—	5.0× / 0.2
Derelicts · Bay of Bengal	1	14.5	0	—	0.4× / 2.8
Spills · Caribbean Sea	1	14	0	—	new / 0
Incidents · Celtic Sea	1	13.9	0	—	new / 0
Cable ops · Irish Sea and St. George's Channel	1	12.7	0	—	new / 0
Surveys · Mozambique Channel	1	11.5	0	—	5.0× / 0.2
Missiles · Laptev Sea	1	10.4	0	—	0.8× / 1.2
Exercises · Norwegian Sea	1	9	0	—	1.7× / 0.6
Exercises · East Siberian Sea	1	7.9	0	—	new / 0
Other · Arabian Sea	1	6.7	1	6	2.5× / 0.4
Incidents · Japan Sea	1	6.7	1	6	1.7× / 0.6
Incidents · Makassar Strait	1	6.7	0	—	5.0× / 0.2
Exercises · Kara Sea	1	6.4	0	—	1.7× / 0.6
Restricted · South Atlantic Ocean	1	5.7	0	—	new / 0
Missiles · Gulf of Mexico	1	3.9	0	—	new / 0
Incidents · Bismarck Sea	1	3.8	0	—	0.5× / 2.2
Incidents · Ionian Sea	1	3.7	1	3	2.5× / 0.4
Exercises · Persian Gulf	1	3.4	0	—	1.7× / 0.6
Quakes · Banda Sea	1	3.2	0	—	1.0× / 1
Derelicts · Bay of Biscay	1	3	0	—	1.7× / 0.6
Exercises · Bering Sea	1	3	0	—	new / 0
Quakes · Eastern China Sea	1	3	0	—	5.0× / 0.2
Storms · Gulf of Mexico	1	3	0	—	0.1× / 6.8
Derelicts · Ionian Sea	1	3	0	—	new / 0
Quakes · Java Sea	1	3	0	—	1.7× / 0.6
Icebergs · Kara Sea	1	3	0	—	1.7× / 0.6
Quakes · Makassar Strait	1	3	0	—	0.7× / 1.4
Quakes · Molukka Sea	1	3	0	—	5.0× / 0.2
Quakes · North Atlantic Ocean	1	3	0	—	0.6× / 1.6
Other · North Atlantic Ocean	1	3	0	—	0.4× / 2.6
Quakes · Philippine Sea	1	3	0	—	0.2× / 4.4
Derelicts · Sea of Okhotsk	1	3	0	—	new / 0
Quakes · Sea of Okhotsk	1	3	0	—	2.5× / 0.4
Debris · South Atlantic Ocean	1	3	0	—	1.7× / 0.6
Quakes · South China Sea	1	3	0	—	new / 0
Piracy · North Atlantic Ocean	1	2.4	0	—	5.0× / 0.2
Cable ops · North Sea	1	2.3	0	—	0.6× / 1.8
Cable ops · Malacca Strait	1	2	1	1	new / 0
Nav aids · South China Sea	1	1.7	0	—	new / 0
Missiles · Coral Sea	1	1.6	0	—	5.0× / 0.2
Exercises · Sea of Okhotsk	1	1.6	1	1	2.5× / 0.4
Nav aids · English Channel	1	1.4	0	—	0.3× / 3
Icebergs · North Atlantic Ocean	1	1.2	0	—	new / 0
Debris · Norwegian Sea	1	1.2	0	—	new / 0
Derelicts · South China Sea	1	1	0	—	1.3× / 0.8
Missiles · Arctic Ocean	1	0.5	1	0	1.7× / 0.6
Incidents · Beaufort Sea	1	0.4	1	0	new / 0
Incidents · Solomon Sea	1	0.4	1	0	1.3× / 0.8
Nav aids · Irish Sea and St. George's Channel	1	0.2	0	—	0.6× / 1.8
Wrecks · South Atlantic Oceanlong running	0	180	6	491	0.0× / 0.8
Exercises · Aegean Sea	0	150	5	271	0.0× / 6.2
Wrecks · Arabian Sea	0	150	5	356	0.0× / 1.2
Surveys · The Northwestern Passageslong running	0	150	5	407	0.0× / 0.8
Nav aids · Beaufort Sealong running	0	120	4	415	0.0× / 1.2
Wrecks · Caribbean Sea	0	120	4	202	0.0× / 0.2
Nav aids · Laccadive Sealong running	0	120	4	473	0.0× / 0.4
Ordnance · Bay of Biscay	0	90	3	103	— / 0
Surveys · Black Sea	0	90	3	240	0.0× / 0.8
Wrecks · Hudson Bay	0	90	3	337	— / 0
Surveys · Kara Sealong running	0	90	3	446	0.0× / 1.2
Wrecks · Persian Gulflong running	0	90	3	591	— / 0
Wrecks · South China Sealong running	0	90	3	1,668	0.0× / 1
Nav aids · The Northwestern Passages	0	89	2	110	0.0× / 1.6
Wrecks · Laccadive Sea	0	80.6	2	225	0.0× / 0.2
Nav aids · Bering Sea	0	60	2	281	0.0× / 0.2
Wrecks · Coral Sealong running	0	60	2	456	— / 0
Other · Persian Gulf	0	60	2	226	0.0× / 0.2
Other · South Atlantic Ocean	0	60	2	154	0.0× / 0.8
Structures · South Atlantic Oceanlong running	0	60	2	428	0.0× / 1
Cable ops · Chukchi Sea	0	36	0	—	— / 0
Surveys · Norwegian Sea	0	35.4	0	—	0.0× / 0.8
Surveys · Bay of Biscay	0	31	1	128	0.0× / 1.2
Derelicts · South Atlantic Ocean	0	30.1	1	196	0.0× / 1.8
Missiles · Aegean Sea	0	30	1	271	— / 0
Other · Arafura Sea	0	30	1	46	0.0× / 0.4
Wrecks · Arafura Sea	0	30	1	152	— / 0
Nav aids · Arctic Oceanlong running	0	30	1	374	0.0× / 0.2
Nav aids · Barentsz Sea	0	30	1	322	0.0× / 0.2
Surveys · Bass Strait	0	30	1	177	0.0× / 0.2
Other · Bay of Bengal	0	30	1	56	0.0× / 1.6
Wrecks · Bay of Bengal	0	30	1	66	— / 0
Debris · Bay of Biscaylong running	0	30	1	388	0.0× / 0.4
Nav aids · Bay of Biscaylong running	0	30	1	428	0.0× / 0.2
Other · Bay of Biscay	0	30	1	255	— / 0
Cable ops · Beaufort Sea	0	30	1	31	— / 0
Surveys · Beaufort Sea	0	30	1	52	— / 0

Cite: seahazards.com Sea Ledger, 2023-09, retrieved 2026-09-03

Not for navigation. Warning-days = days each warning was in force within the month, summed. Only warnings we display are counted; the ratio compares warnings issued with the mean of the reference months.