Sea Ledger, December 2020

2020-12-01 to 2020-12-31 · archive

issued: 645
warning-days in force: 9,206
in force at month end: 250
sea × type cells: 225

baseline: same month, previous 5 years (2019-12, 2018-12, 2017-12, 2016-12, 2015-12)

By type

type	issued	warning-days	in force at end
Exercises	133	1,527.1	25
Incidents	115	982.5	35
Icebergs	90	95.6	4
Surveys	57	1,419.7	49
Nav aids	54	1,836.8	52
Missiles	52	624.3	2
Derelicts	34	128.9	3
Cable ops	25	529.8	17
Quakes	23	76.3	2
Other	13	311.4	11
Piracy	13	86.1	1
Spills	11	148	6
Debris	10	29.9	0
Restricted	6	125.7	4
Wrecks	4	1,106.2	33
Volcanic	2	75.5	3
Containers	2	8.7	0
Mines	1	31	1
Structures	0	31	1
Ordnance	0	31	1

By sea and type · 200 cells, most issued first

cell	issued	warning-days	at end	longest d	vs 5 y
Incidents · South China Sea	44	365.7	18	326	1.3× / 34.6
Icebergs · Labrador Sea	31	36.9	2	32	1.1× / 27.4
Icebergs · South Atlantic Ocean	31	30.8	1	31	1.1× / 27.2
Icebergs · Southern Oceansurge	28	27.9	1	31	2.2× / 12.6
Exercises · Black Seasurge	21	315.4	6	65	2.5× / 8.4
Incidents · North Pacific Ocean	20	191.9	2	46	1.1× / 17.4
Exercises · North Pacific Ocean	18	210.1	7	65	1.2× / 14.8
Exercises · Arabian Seasurge	16	136.8	2	38	2.0× / 8
Exercises · Mediterranean Sea - Eastern Basin	15	89.2	2	364	0.9× / 16.2
Surveys · North Atlantic Oceansurge	14	343.1	20	328	3.0× / 4.6
Missiles · Barentsz Seasurge	13	98	0	—	2.5× / 5.2
Surveys · South Atlantic Ocean	12	142.1	3	88	1.0× / 11.8
Exercises · South Pacific Oceansurge	12	35.8	0	—	2.3× / 5.2
Piracy · Gulf of Guineasurge	11	72.1	1	29	3.2× / 3.4
Nav aids · North Sea	11	51.9	1	95	1.2× / 9.2
Exercises · Aegean Sealong running	10	212.1	1	367	0.8× / 13
Missiles · North Atlantic Ocean	10	87.6	0	—	1.1× / 8.8
Missiles · South Pacific Oceansurge	9	50.8	0	—	2.1× / 4.2
Exercises · Yellow Sea	9	50.1	2	34	1.3× / 6.8
Quakes · North Pacific Ocean	9	28.9	1	31	1.1× / 7.8
Derelicts · North Atlantic Ocean	8	26	0	—	1.6× / 5
Nav aids · Caribbean Seasurge	7	241.7	8	120	2.2× / 3.2
Exercises · Bay of Bengal	7	81.2	0	—	0.6× / 11.4
Incidents · South Pacific Ocean	7	79.7	2	33	1.5× / 4.8
Surveys · Aegean Seasurge	7	26	0	—	7.0× / 1
Quakes · South Pacific Ocean	7	23	0	—	0.6× / 11.6
Incidents · Indian Ocean	7	21.3	2	25	1.8× / 3.8
Nav aids · North Atlantic Oceanlong running	6	176.6	6	509	1.0× / 6
Exercises · South Atlantic Ocean	6	79.9	0	—	0.8× / 8
Derelicts · Timor Seanew	6	12.9	0	—	new / 0
Nav aids · South Pacific Oceansurgelong running	5	303.3	10	787	2.3× / 2.2
Surveys · Persian Gulfsurgelong running	5	152.4	4	583	2.1× / 2.4
Exercises · North Atlantic Ocean	5	61	2	86	0.8× / 6.4
Missiles · Japan Seasurge	5	45.5	0	—	25× / 0.2
Exercises · Japan Seasurge	5	23.2	0	—	25× / 0.2
Derelicts · South China Sea	5	10	0	—	1.5× / 3.4
Cable ops · Aegean Seasurge	4	68.8	2	58	20× / 0.2
Cable ops · Eastern China Seasurge	4	32.6	1	28	4.0× / 1
Debris · Arafura Seasurge	4	12	0	—	5.0× / 0.8
Nav aids · Bering Seanew	4	10.7	1	28	new / 0
Surveys · Strait of Gibraltarnew	4	10.5	0	—	new / 0
Incidents · Timor Sea	4	7.7	0	—	1.3× / 3
Incidents · Coral Sea	4	0.3	0	—	0.9× / 4.4
Surveys · Mediterranean Sea - Eastern Basin	3	119.4	4	188	0.7× / 4.2
Nav aids · Inner Seas off the West Coast of Scotlandlong running	3	86.9	1	385	0.9× / 3.2
Restricted · South Atlantic Oceansurge	3	75.9	2	364	15× / 0.2
Missiles · Indian Ocean	3	60	0	—	0.7× / 4.6
Spills · North Pacific Ocean	3	42	0	—	1.7× / 1.8
Cable ops · Mediterranean Sea - Eastern Basinsurge	3	32.6	1	29	5.0× / 0.6
Cable ops · Irish Sea and St. George's Channelnew	3	26.3	1	28	new / 0
Incidents · Gulf of Thailand	3	24.6	2	36	1.9× / 1.6
Restricted · Japan Seanew	3	18.8	1	23	new / 0
Quakes · Philippine Sea	3	9	0	—	1.9× / 1.6
Derelicts · South Pacific Ocean	3	9	0	—	1.0× / 3
Debris · South Pacific Oceansurge	3	6.7	0	—	7.5× / 0.4
Incidents · Tasman Sea	3	1.3	0	—	1.3× / 2.4
Incidents · Great Australian Bightsurge	3	0.2	0	—	7.5× / 0.4
Nav aids · Gulf of Mexico	2	100.8	3	99	0.9× / 2.2
Surveys · Arabian Sea	2	79.9	2	59	0.3× / 7
Wrecks · North Pacific Oceannewlong running	2	46	1	637	new / 0
Incidents · Laccadive Sea	2	45.8	1	44	0.7× / 3
Incidents · Java Sea	2	41.6	1	297	0.9× / 2.2
Exercises · Laccadive Sea	2	34.3	1	34	1.1× / 1.8
Spills · Gulf of Mexico	2	33	1	37	0.6× / 3.6
Incidents · Celebes Sea	2	29.4	2	17	5.0× / 0.4
Other · Davis Strait	2	29.2	2	14	1.4× / 1.4
Nav aids · English Channel	2	28.7	0	—	0.8× / 2.4
Cable ops · Philippine Sea	2	27.5	1	27	3.3× / 0.6
Volcanic · Philippine Sea	2	27	2	13	5.0× / 0.4
Cable ops · Yellow Sea	2	20.2	1	25	10× / 0.2
Cable ops · Arabian Sea	2	20.1	1	20	5.0× / 0.4
Spills · Gulf of Alaska	2	20	1	16	10× / 0.2
Missiles · North Pacific Ocean	2	19.9	0	—	0.4× / 5.2
Spills · The Coastal Waters of Southeast Alaska and British Columbia	2	18	2	9	3.3× / 0.6
Surveys · Laccadive Sea	2	16.1	1	16	10× / 0.2
Containers · North Pacific Ocean	2	8.7	0	—	3.3× / 0.6
Exercises · Andaman or Burma Sea	2	7.9	0	—	2.5× / 0.8
Missiles · Baffin Baynew	2	7.7	0	—	new / 0
Derelicts · Bay of Bengal	2	6.4	0	—	1.1× / 1.8
Missiles · South China Sea	2	6.1	0	—	10× / 0.2
Debris · Indian Ocean	2	6	0	—	10× / 0.2
Incidents · South Atlantic Ocean	2	4.1	1	31	0.2× / 9.8
Other · Bering Seanew	2	4	0	—	new / 0
Exercises · Philippine Sea	2	2.4	0	—	0.6× / 3.6
Derelicts · English Channelnew	2	2.2	0	—	new / 0
Nav aids · Celtic Sea	2	1.7	0	—	0.8× / 2.4
Nav aids · Irish Sea and St. George's Channel	2	0.6	0	—	1.1× / 1.8
Wrecks · Persian Gulflong running	1	280.8	10	547	1.7× / 0.6
Nav aids · North Pacific Oceanlong running	1	143.4	2	517	0.1× / 7.2
Missiles · Black Sea	1	124.4	1	32	0.4× / 2.8
Surveys · Black Sea	1	100.5	4	197	0.5× / 2
Other · South Pacific Ocean	1	91.8	3	287	1.7× / 0.6
Other · Persian Gulf	1	88.3	3	178	new / 0
Nav aids · Arabian Sealong running	1	69.5	2	420	1.0× / 1
Incidents · Arabian Sea	1	66.6	0	—	0.4× / 2.6
Cable ops · South Atlantic Ocean	1	60.9	1	35	0.2× / 4.4
Surveys · Mediterranean Sea - Western Basin	1	52.5	0	—	2.5× / 0.4
Cable ops · Black Sea	1	35.8	2	113	5.0× / 0.2
Derelicts · Arabian Sea	1	34	1	342	0.5× / 2.2
Nav aids · Persian Gulf	1	31.3	2	260	2.5× / 0.4
Mines · English Channel	1	31	1	69	new / 0
Nav aids · Norwegian Sea	1	31	1	139	2.5× / 0.4
Surveys · Mozambique Channel	1	30.6	1	31	new / 0
Cable ops · North Atlantic Ocean	1	20.4	1	20	0.5× / 2.2
Missiles · Arctic Ocean	1	19.8	0	—	1.3× / 0.8
Spills · Caribbean Sea	1	17	1	35	new / 0
Incidents · North Atlantic Ocean	1	14.9	0	—	0.1× / 15.4
Derelicts · Andaman or Burma Sea	1	12.6	1	12	new / 0
Cable ops · Gulf of Guinea	1	12.1	0	—	5.0× / 0.2
Missiles · Sea of Okhotsk	1	11.2	0	—	new / 0
Incidents · Bay of Bengal	1	10.3	1	10	1.7× / 0.6
Incidents · Bismarck Sea	1	9.4	1	9	0.5× / 2.2
Exercises · Indian Ocean	1	8.3	1	8	0.4× / 2.4
Missiles · Davis Strait	1	8.1	0	—	1.7× / 0.6
Other · Gulf of Mexico	1	7.9	0	—	1.0× / 1
Incidents · Malacca Strait	1	7.9	0	—	2.5× / 0.4
Incidents · Flores Sea	1	7.8	1	7	new / 0
Piracy · North Atlantic Ocean	1	7	0	—	new / 0
Piracy · Singapore Strait	1	7	0	—	2.5× / 0.4
Wrecks · Japan Sea	1	6.6	1	6	new / 0
Other · Mediterranean Sea - Western Basin	1	5.9	0	—	new / 0
Cable ops · Indian Ocean	1	5.6	1	5	1.7× / 0.6
Debris · Timor Sea	1	5.2	0	—	2.5× / 0.4
Spills · North Atlantic Ocean	1	5	1	42	0.5× / 2
Missiles · Philippine Sea	1	5	0	—	2.5× / 0.4
Missiles · Laccadive Sea	1	4.8	0	—	1.0× / 1
Nav aids · Coral Sea	1	4.6	0	—	0.2× / 4.6
Surveys · Tasman Sea	1	4.3	0	—	1.7× / 0.6
Incidents · Persian Gulf	1	3.5	0	—	2.5× / 0.4
Exercises · Red Sea	1	3.4	0	—	5.0× / 0.2
Incidents · Celtic Sea	1	3	0	—	5.0× / 0.2
Derelicts · Indian Ocean	1	3	0	—	0.3× / 3.6
Quakes · Indian Ocean	1	3	0	—	0.5× / 2
Derelicts · Java Sea	1	3	0	—	5.0× / 0.2
Derelicts · Mediterranean Sea - Western Basin	1	3	0	—	1.7× / 0.6
Derelicts · Mozambique Channel	1	3	0	—	new / 0
Quakes · Norwegian Sea	1	3	0	—	new / 0
Derelicts · Persian Gulf	1	3	0	—	new / 0
Quakes · Southern Ocean	1	3	0	—	new / 0
Nav aids · Great Australian Bight	1	2.9	0	—	0.5× / 2
Incidents · Mozambique Channel	1	2.6	0	—	1.7× / 0.6
Surveys · North Pacific Ocean	1	2.2	0	—	5.0× / 0.2
Surveys · Bass Strait	1	2.1	0	—	1.3× / 0.8
Nav aids · Indian Ocean	1	2.1	0	—	0.8× / 1.2
Quakes · South Atlantic Ocean	1	2	1	2	0.8× / 1.2
Surveys · Indian Ocean	1	1.8	0	—	0.4× / 2.4
Other · Mozambique Channel	1	1.5	1	1	new / 0
Nav aids · Kara Sea	1	1.2	0	—	5.0× / 0.2
Nav aids · Bristol Channel	1	1	0	—	new / 0
Incidents · Black Sea	1	0.9	0	—	5.0× / 0.2
Exercises · Persian Gulf	1	0.9	0	—	new / 0
Derelicts · Arafura Sea	1	0.8	1	0	5.0× / 0.2
Other · Hudson Bay	1	0.8	0	—	new / 0
Incidents · Bass Strait	1	0.7	1	0	2.5× / 0.4
Surveys · Andaman or Burma Sea	1	0.6	1	0	1.7× / 0.6
Incidents · Halmahera Sea	1	0.5	0	—	5.0× / 0.2
Other · North Atlantic Ocean	1	0.3	0	—	0.6× / 1.8
Nav aids · Davis Strait	1	0.2	0	—	1.3× / 0.8
Other · Coral Sea	1	0	0	—	5.0× / 0.2
Other · Gulf of Alaska	1	0	0	—	new / 0
Wrecks · South China Sealong running	0	279	9	683	0.0× / 1.2
Wrecks · North Atlantic Oceanlong running	0	124	4	710	0.0× / 0.2
Nav aids · South Atlantic Ocean	0	107.4	3	66	0.0× / 6.2
Nav aids · Mediterranean Sea - Western Basin	0	93	3	214	0.0× / 0.6
Exercises · Ionian Sea	0	92.4	0	—	0.0× / 1.8
Surveys · South Pacific Oceanlong running	0	72	1	456	0.0× / 0.6
Exercises · Mediterranean Sea - Western Basin	0	69.6	1	364	0.0× / 0.6
Nav aids · Laccadive Sealong running	0	62.5	2	608	0.0× / 0.8
Wrecks · Arabian Sealong running	0	62	2	464	0.0× / 0.8
Surveys · Arctic Ocean	0	62	2	73	— / 0
Nav aids · Bay of Bengal	0	62	2	204	0.0× / 0.8
Wrecks · Inner Seas off the West Coast of Scotland	0	62	2	83	— / 0
Wrecks · Caribbean Sea	0	35.1	0	—	0.0× / 0.8
Nav aids · Gulf of California	0	35.1	0	—	— / 0
Wrecks · South Atlantic Ocean	0	34.6	1	157	0.0× / 1
Wrecks · English Channel	0	31.9	1	49	0.0× / 1
Missiles · Aegean Sea	0	31	1	208	0.0× / 0.8
Nav aids · Alboran Sea	0	31	1	98	— / 0
Nav aids · Andaman or Burma Sealong running	0	31	1	581	0.0× / 0.6
Other · Arabian Sealong running	0	31	1	615	0.0× / 0.2
Surveys · Barentsz Sea	0	31	1	73	0.0× / 0.4
Surveys · Bay of Bengal	0	31	1	34	0.0× / 2.8
Surveys · Bering Sea	0	31	1	71	— / 0
Cable ops · Caribbean Sea	0	31	1	34	0.0× / 0.6
Surveys · Caribbean Sea	0	31	1	36	0.0× / 0.2
Nav aids · Gulf of Thailandlong running	0	31	1	441	— / 0
Nav aids · Mediterranean Sea - Eastern Basin	0	31	1	147	0.0× / 0.2
Other · Mediterranean Sea - Eastern Basin	0	31	1	98	0.0× / 0.2
Cable ops · Mediterranean Sea - Western Basin	0	31	1	64	0.0× / 1
Nav aids · Mozambique Channel	0	31	1	78	— / 0
Volcanic · Mozambique Channellong running	0	31	1	455	— / 0
Wrecks · Mozambique Channel	0	31	1	78	— / 0
Cable ops · North Pacific Ocean	0	31	1	121	— / 0
Ordnance · North Sealong running	0	31	1	444	0.0× / 0.8
Cable ops · Persian Gulf	0	31	1	39	0.0× / 0.4
Restricted · Persian Gulflong running	0	31	1	624	— / 0
Wrecks · Red Sealong running	0	31	1	383	0.0× / 0.2
Surveys · Sea of Okhotsk	0	31	1	269	0.0× / 0.4
Structures · South China Sealong running	0	31	1	402	— / 0
Surveys · South China Sealong running	0	31	1	476	0.0× / 0.6

Cite: seahazards.com Sea Ledger, 2020-12, 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.