Sea Ledger, April 2020

2020-04-01 to 2020-04-30 · archive

issued: 575
warning-days in force: 10,771
in force at month end: 347
sea × type cells: 211

baseline: same month, previous 5 years (2019-04, 2018-04, 2017-04, 2016-04, 2015-04)

By type

type	issued	warning-days	in force at end
Exercises	148	1,233.5	35
Icebergs	90	98.1	4
Incidents	80	682.2	22
Surveys	75	2,153.6	73
Nav aids	58	2,656.2	94
Missiles	33	488.2	9
Debris	19	60.3	2
Cable ops	16	354	11
Quakes	15	47.5	0
Spills	13	168	6
Derelicts	10	125.6	3
Other	7	469.3	14
Piracy	5	51.1	2
Wrecks	4	1,807.4	60
Ordnance	2	68.5	2
Restricted	0	150	5
Structures	0	37.4	1
Mines	0	30	1
Volcanic	0	90	3

By sea and type · 200 cells, most issued first

cell	issued	warning-days	at end	longest d	vs 5 y
Icebergs · Southern Oceansurge	48	46.4	2	30	2.8× / 17
Exercises · Mediterranean Sea - Eastern Basinsurge	37	162.7	5	119	4.3× / 8.6
Exercises · North Pacific Ocean	31	143.8	5	65	1.6× / 19.8
Icebergs · Labrador Seasurge	29	34.1	2	31	2.6× / 11
Incidents · South China Sea	27	288.1	10	104	1.1× / 23.4
Exercises · Aegean Seasurge	23	359.8	13	122	5.5× / 4.2
Exercises · Black Seasurge	22	183.5	3	63	2.1× / 10.6
Surveys · South Atlantic Ocean	17	287.6	8	181	1.1× / 14.8
Nav aids · South Atlantic Ocean	14	233.9	10	202	1.5× / 9.4
Surveys · Persian Gulfsurge	11	194.9	5	338	4.2× / 2.6
Incidents · North Pacific Ocean	11	112.1	6	46	0.5× / 24.6
Icebergs · South Atlantic Ocean	11	11.6	0	—	0.7× / 15.2
Nav aids · North Atlantic Ocean	9	278	9	264	1.7× / 5.2
Missiles · North Pacific Oceansurge	9	118.2	1	231	2.5× / 3.6
Surveys · South Pacific Oceansurge	8	110.1	3	211	6.7× / 1.2
Debris · South Pacific Oceansurge	8	8.8	0	—	13× / 0.6
Incidents · Indian Ocean	8	3.9	0	—	1.8× / 4.4
Surveys · Arabian Sea	7	159	8	135	1.1× / 6.2
Missiles · Black Sea	7	147.7	5	32	1.8× / 3.8
Incidents · North Atlantic Ocean	7	122.1	2	230	0.6× / 12.4
Exercises · Yellow Sea	7	37.3	1	32	0.8× / 8.4
Exercises · Mediterranean Sea - Western Basinsurge	6	57.8	1	119	15× / 0.4
Missiles · Barentsz Sea	6	38.7	2	27	1.5× / 4
Exercises · South Atlantic Ocean	6	37.7	1	43	1.4× / 4.4
Incidents · South Atlantic Ocean	6	25.1	1	27	0.8× / 7.8
Incidents · Coral Sea	6	1.2	0	—	1.1× / 5.2
Surveys · North Atlantic Oceanlong running	5	544.9	18	896	0.8× / 6.6
Nav aids · South Pacific Oceanlong running	5	282.1	11	542	1.7× / 3
Exercises · North Atlantic Ocean	5	44.3	1	92	1.1× / 4.6
Surveys · Mediterranean Sea - Eastern Basin	4	140.4	4	131	0.9× / 4.2
Nav aids · North Sea	4	110.6	3	72	0.5× / 8.8
Piracy · Gulf of Guinea	4	44.1	2	41	0.9× / 4.2
Spills · North Pacific Ocean	4	43	2	25	1.5× / 2.6
Incidents · South Pacific Ocean	4	25.8	1	38	0.6× / 6.8
Debris · Indian Oceansurge	4	8.2	0	—	2.5× / 1.6
Nav aids · North Pacific Oceanlong running	3	133.8	7	429	1.3× / 2.4
Nav aids · Indian Oceansurgelong running	3	117.7	3	392	2.5× / 1.2
Surveys · Bay of Bengal	3	51.1	2	45	1.3× / 2.4
Incidents · Java Seasurge	3	46.7	1	52	5.0× / 0.6
Cable ops · Mediterranean Sea - Eastern Basin	3	29.6	2	14	1.7× / 1.8
Cable ops · Mediterranean Sea - Western Basinsurge	3	22.9	0	—	3.0× / 1
Cable ops · Arabian Seasurge	3	21.5	1	21	2.1× / 1.4
Spills · Gulf of Mexico	3	21	2	21	0.4× / 6.8
Nav aids · Bay of Bengalsurge	3	20.6	3	13	3.8× / 0.8
Surveys · North Pacific Oceansurge	3	10.4	0	—	15× / 0.2
Quakes · South Pacific Ocean	3	9.8	0	—	0.3× / 9.4
Quakes · Philippine Sea	3	9	0	—	0.8× / 3.8
Nav aids · Caribbean Sealong running	2	399.4	14	814	3.3× / 0.6
Nav aids · Coral Sea	2	92.8	3	310	0.3× / 8
Surveys · Bass Strait	2	68.1	2	50	10× / 0.2
Nav aids · Inner Seas off the West Coast of Scotland	2	62.3	1	140	0.5× / 4
Surveys · Tasman Sea	2	58.8	2	64	10× / 0.2
Surveys · Black Sea	2	45.6	3	52	2.0× / 1
Cable ops · Philippine Sea	2	37.3	1	66	3.3× / 0.6
Missiles · Sea of Okhotsknew	2	34	0	—	new / 0
Nav aids · Persian Gulf	2	31.7	2	16	10× / 0.2
Surveys · Sea of Marmara	2	30.5	2	108	2.5× / 0.8
Cable ops · Bay of Bengal	2	28.6	1	48	3.3× / 0.6
Spills · Gulf of Alaska	2	28	0	—	2.0× / 1
Missiles · North Atlantic Ocean	2	26.2	0	—	0.3× / 7.8
Spills · North Atlantic Ocean	2	24	2	14	0.9× / 2.2
Exercises · Sea of Okhotsk	2	23.9	0	—	10× / 0.2
Missiles · Japan Sea	2	23.1	0	—	0.8× / 2.6
Debris · Persian Gulf	2	16.4	1	16	10× / 0.2
Nav aids · English Channel	2	15.9	1	15	0.8× / 2.4
Missiles · Arabian Sea	2	15.2	0	—	2.5× / 0.8
Surveys · North Sea	2	12.8	1	42	1.7× / 1.2
Incidents · Tasman Sea	2	10.9	0	—	2.0× / 1
Surveys · Mediterranean Sea - Western Basin	2	10.1	1	204	3.3× / 0.6
Derelicts · Caribbean Sea	2	8.6	0	—	3.3× / 0.6
Ordnance · North Pacific Ocean	2	8.5	0	—	10× / 0.2
Exercises · South Pacific Ocean	2	8.4	1	26	0.3× / 6.4
Incidents · Black Seanew	2	8.2	0	—	new / 0
Quakes · Indian Ocean	2	7.7	0	—	0.8× / 2.6
Derelicts · North Atlantic Ocean	2	7.5	0	—	0.6× / 3.2
Derelicts · Indian Ocean	2	6	0	—	0.6× / 3.6
Icebergs · Kara Sea	2	6	0	—	3.3× / 0.6
Quakes · Molukka Sea	2	6	0	—	2.5× / 0.8
Quakes · North Pacific Ocean	2	6	0	—	0.4× / 4.8
Missiles · South Pacific Ocean	2	5	0	—	0.8× / 2.6
Nav aids · Celtic Sea	2	4.7	0	—	2.5× / 0.8
Wrecks · South China Sealong running	1	528.4	17	479	0.7× / 1.4
Wrecks · Caribbean Sealong running	1	268.1	9	1,186	2.5× / 0.4
Nav aids · Gulf of Mexico	1	111.9	4	98	0.3× / 3
Wrecks · Persian Gulf	1	91.6	4	302	new / 0
Surveys · Indian Ocean	1	82.2	2	139	0.6× / 1.8
Wrecks · South Atlantic Ocean	1	73.1	2	133	1.3× / 0.8
Nav aids · Bass Strait	1	60.1	2	131	1.0× / 1
Spills · The Coastal Waters of Southeast Alaska and British Columbia	1	38	0	—	2.5× / 0.4
Exercises · Arabian Sea	1	30.9	1	34	0.1× / 8.8
Cable ops · Aegean Sea	1	30	1	161	new / 0
Nav aids · Norwegian Sea	1	30	1	63	5.0× / 0.2
Missiles · Arctic Ocean	1	27.8	0	—	new / 0
Surveys · Sea of Okhotsk	1	24.6	1	24	new / 0
Incidents · Philippine Sea	1	22.9	1	46	0.2× / 4.4
Surveys · Tyrrhenian Sea	1	20.8	1	20	new / 0
Other · Solomon Sea	1	20	0	—	new / 0
Debris · South Atlantic Ocean	1	15.2	1	15	new / 0
Spills · Bering Sea	1	14	0	—	2.5× / 0.4
Exercises · Bay of Bengal	1	13.6	0	—	0.1× / 8.2
Surveys · Norwegian Sea	1	10.1	1	10	0.6× / 1.6
Surveys · Gulf of Suez	1	10	0	—	1.7× / 0.6
Cable ops · Coral Sea	1	9	0	—	new / 0
Exercises · Japan Sea	1	7.5	0	—	new / 0
Piracy · South China Sea	1	7	0	—	1.7× / 0.6
Cable ops · South Atlantic Ocean	1	6.5	0	—	0.6× / 1.6
Exercises · Caribbean Sea	1	3.7	0	—	0.7× / 1.4
Debris · Arafura Sea	1	3	0	—	5.0× / 0.2
Quakes · Banda Sea	1	3	0	—	0.8× / 1.2
Derelicts · Bay of Biscay	1	3	0	—	new / 0
Debris · Caribbean Sea	1	3	0	—	5.0× / 0.2
Quakes · Caribbean Sea	1	3	0	—	new / 0
Debris · English Channel	1	3	0	—	2.5× / 0.4
Derelicts · Mediterranean Sea - Eastern Basin	1	3	0	—	0.7× / 1.4
Other · Mozambique Channel	1	3	0	—	5.0× / 0.2
Quakes · Solomon Sea	1	3	0	—	1.0× / 1
Derelicts · South Pacific Ocean	1	3	0	—	0.4× / 2.6
Debris · North Atlantic Ocean	1	2.7	0	—	0.7× / 1.4
Other · The Coastal Waters of Southeast Alaska and British Columbia	1	2.6	0	—	new / 0
Exercises · Coral Sea	1	2.4	0	—	1.3× / 0.8
Exercises · Barentsz Sea	1	2.1	0	—	0.8× / 1.2
Derelicts · South Atlantic Ocean	1	2	0	—	0.6× / 1.6
Nav aids · Ionian Sea	1	1.9	0	—	2.5× / 0.4
Incidents · Labrador Sea	1	1.2	0	—	new / 0
Nav aids · Gulf of Alaska	1	0.8	0	—	1.3× / 0.8
Exercises · Gulf of Mexico	1	0.7	0	—	0.5× / 2
Incidents · Arafura Sea	1	0.5	0	—	1.7× / 0.6
Other · North Sea	1	0.4	1	0	0.7× / 1.4
Other · North Atlantic Ocean	1	0.3	0	—	0.2× / 6.2
Other · Mediterranean Sea - Eastern Basin	1	0.2	0	—	0.6× / 1.8
Incidents · Timor Sea	1	0.2	0	—	2.5× / 0.4
Other · North Pacific Ocean	1	0.1	0	—	1.3× / 0.8
Other · Caribbean Sealong running	0	180	6	1,196	0.0× / 0.6
Wrecks · North Atlantic Oceanlong running	0	180	6	910	0.0× / 0.4
Wrecks · North Pacific Oceanlong running	0	120	4	1,049	0.0× / 0.8
Nav aids · Arabian Sealong running	0	90	3	394	0.0× / 1.4
Exercises · Ionian Sea	0	90	3	122	0.0× / 0.4
Nav aids · Philippine Sealong running	0	90	3	421	— / 0
Surveys · South China Sea	0	90	3	240	0.0× / 1.6
Other · South Pacific Ocean	0	90	3	50	0.0× / 0.4
Other · Arabian Sealong running	0	60	2	459	0.0× / 0.8
Wrecks · East Siberian Sea	0	60	2	34	— / 0
Wrecks · Gulf of Mexicolong running	0	60	2	1,141	0.0× / 0.2
Nav aids · Mozambique Channel	0	60	2	339	— / 0
Ordnance · North Sea	0	60	2	199	0.0× / 1.8
Restricted · Persian Gulflong running	0	60	2	379	0.0× / 0.4
Volcanic · Philippine Sea	0	60	2	136	0.0× / 0.4
Restricted · South Atlantic Ocean	0	60	2	119	0.0× / 0.2
Cable ops · South China Sea	0	60	2	52	0.0× / 2.2
Wrecks · South Pacific Ocean	0	60	2	91	0.0× / 0.4
Nav aids · Tasman Sea	0	60	2	52	0.0× / 0.4
Nav aids · Bering Sea	0	59	0	—	— / 0
Surveys · Great Australian Bight	0	39.2	1	56	0.0× / 0.6
Cable ops · North Atlantic Ocean	0	30.5	1	92	0.0× / 4.8
Nav aids · Aegean Sealong running	0	30	1	394	0.0× / 0.4
Missiles · Aegean Sea	0	30	1	121	— / 0
Nav aids · Andaman or Burma Sea	0	30	1	336	0.0× / 1.2
Derelicts · Arabian Sea	0	30	1	97	0.0× / 0.2
Wrecks · Arabian Sea	0	30	1	219	0.0× / 1.2
Nav aids · Arafura Sea	0	30	1	54	0.0× / 0.8
Surveys · Arctic Ocean	0	30	1	203	— / 0
Surveys · Beaufort Sea	0	30	1	148	— / 0
Surveys · Bering Sea	0	30	1	235	0.0× / 0.2
Cable ops · Bismarck Sea	0	30	1	31	— / 0
Other · Black Sea	0	30	1	184	0.0× / 0.2
Surveys · Caribbean Sea	0	30	1	90	0.0× / 1.4
Wrecks · Celtic Sea	0	30	1	38	— / 0
Wrecks · English Channel	0	30	1	35	0.0× / 0.4
Nav aids · Great Australian Bight	0	30	1	253	0.0× / 0.2
Wrecks · Great Australian Bight	0	30	1	325	0.0× / 0.2
Wrecks · Gulf of Californialong running	0	30	1	562	— / 0
Wrecks · Gulf of Guinea	0	30	1	211	0.0× / 0.2
Nav aids · Gulf of Thailand	0	30	1	196	— / 0
Wrecks · Gulf of Thailand	0	30	1	110	— / 0
Cable ops · Indian Ocean	0	30	1	241	0.0× / 0.4
Wrecks · Indian Oceanlong running	0	30	1	367	0.0× / 0.6
Derelicts · Inner Seas off the West Coast of Scotland	0	30	1	38	— / 0
Nav aids · Laccadive Sea	0	30	1	363	0.0× / 1.6
Nav aids · Malacca Strait	0	30	1	311	— / 0
Nav aids · Mediterranean Sea - Eastern Basin	0	30	1	258	0.0× / 0.4
Wrecks · Mediterranean Sea - Eastern Basin	0	30	1	113	— / 0
Nav aids · Mediterranean Sea - Western Basin	0	30	1	100	0.0× / 0.4
Volcanic · Mozambique Channel	0	30	1	210	— / 0
Derelicts · North Pacific Ocean	0	30	1	213	0.0× / 1.6
Wrecks · North Sea	0	30	1	218	0.0× / 1.8
Other · Persian Gulf	0	30	1	38	0.0× / 0.4
Mines · Red Sea	0	30	1	62	— / 0
Wrecks · Red Sea	0	30	1	138	— / 0
Wrecks · Singapore Straitlong running	0	30	1	437	— / 0
Structures · South China Sea	0	30	1	157	— / 0
Restricted · South Pacific Ocean	0	30	1	36	0.0× / 0.2
Nav aids · The Coastal Waters of Southeast Alaska and British Columbia	0	30	1	42	0.0× / 1
Surveys · Timor Sea	0	30	1	69	— / 0
Other · Gulf of Alaska	0	27.5	0	—	— / 0
Other · Barentsz Sea	0	22.8	0	—	0.0× / 0.2
Missiles · Indian Ocean	0	22.3	0	—	0.0× / 1.4
Cable ops · Bristol Channel	0	18.1	0	—	— / 0
Exercises · Tyrrhenian Sea	0	15	0	—	— / 0
Nav aids · South China Sea	0	9	0	—	— / 0
Exercises · Andaman or Burma Sea	0	8.4	0	—	0.0× / 2

Cite: seahazards.com Sea Ledger, 2020-04, 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.