Sea Ledger, May 2021

2021-05-01 to 2021-05-31 · archive

issued: 616
warning-days in force: 10,054
in force at month end: 325
sea × type cells: 196

baseline: same month, previous 5 years (2020-05, 2019-05, 2018-05, 2017-05, 2016-05)

By type

type	issued	warning-days	in force at end
Exercises	115	1,319.9	42
Icebergs	92	98.1	4
Incidents	87	731.5	32
Surveys	76	1,857.3	54
Nav aids	62	2,709.2	88
Missiles	46	381	8
Quakes	34	103.9	2
Derelicts	30	183.7	6
Cable ops	27	498	15
Spills	13	208	4
Wrecks	12	1,185.8	45
Other	10	393.4	13
Debris	6	17.4	0
Piracy	2	14	0
Containers	2	6.7	1
Structures	1	35	1
Restricted	1	93.8	3
Volcanic	0	124	4
Ordnance	0	62	2
Mines	0	31	1

By sea and type · 196 cells, most issued first

cell	issued	warning-days	at end	longest d	vs 5 y
Exercises · North Pacific Ocean	34	295.3	12	66	1.5× / 23
Icebergs · Labrador Seasurge	31	37	2	32	2.5× / 12.6
Icebergs · South Atlantic Ocean	31	31.1	1	31	1.8× / 17.6
Icebergs · Southern Ocean	30	30	1	31	1.1× / 27
Incidents · South China Sealong running	19	237.8	9	420	0.8× / 25.4
Surveys · South Atlantic Ocean	18	192.9	7	133	1.4× / 13.2
Exercises · North Atlantic Oceansurge	16	83.4	2	66	2.8× / 5.8
Missiles · North Atlantic Ocean	14	51.3	1	32	1.4× / 10.4
Incidents · Indian Oceansurge	14	17.1	2	30	2.1× / 6.8
Exercises · South Pacific Ocean	13	73.3	3	31	1.8× / 7.4
Incidents · Arabian Seasurge	12	103.6	5	35	4.0× / 3
Quakes · South Pacific Ocean	12	37.9	1	32	1.3× / 9
Exercises · Black Sea	10	169.3	5	96	0.7× / 14.4
Surveys · North Seasurge	10	86.9	2	49	3.1× / 3.2
Derelicts · North Pacific Oceansurge	10	30.6	1	17	5.6× / 1.8
Surveys · North Atlantic Ocean	9	366.1	12	151	1.4× / 6.2
Nav aids · North Atlantic Oceanlong running	9	290.1	9	660	1.6× / 5.6
Nav aids · Inner Seas off the West Coast of Scotlandsurgelong running	9	62	3	536	2.8× / 3.2
Quakes · Indian Oceansurge	9	27	0	—	15× / 0.6
Nav aids · South Atlantic Ocean	8	307.7	13	138	0.8× / 9.6
Surveys · Arabian Sea	8	168.9	4	51	1.1× / 7
Missiles · North Pacific Ocean	8	29.6	0	—	1.4× / 5.8
Quakes · North Pacific Ocean	8	24	1	30	1.2× / 6.8
Cable ops · South Pacific Oceansurge	7	26.6	0	—	35× / 0.2
Surveys · Persian Gulfsurge	6	129.1	4	133	3.0× / 2
Exercises · South Atlantic Ocean	6	114.7	1	34	1.0× / 5.8
Cable ops · North Atlantic Ocean	6	110.3	4	42	0.9× / 6.8
Incidents · Laccadive Seasurge	6	84.7	3	34	15× / 0.4
Spills · North Atlantic Oceansurge	6	79	3	37	2.1× / 2.8
Incidents · South Pacific Ocean	6	21.3	3	12	0.8× / 7.2
Missiles · Black Sea	5	190.6	5	33	1.3× / 3.8
Wrecks · North Atlantic Oceannewlong running	5	153.9	9	861	new / 0
Exercises · Bay of Bengal	5	77.7	2	33	0.6× / 7.8
Exercises · Arabian Sea	5	55.7	2	35	0.8× / 6.2
Incidents · North Pacific Ocean	5	45.7	2	25	0.3× / 19.4
Incidents · South Atlantic Ocean	5	38.3	1	42	0.9× / 5.6
Incidents · Philippine Sea	5	37.2	1	43	1.4× / 3.6
Missiles · Indian Ocean	5	21.3	1	32	1.9× / 2.6
Exercises · Indian Oceansurge	5	5.9	1	12	5.0× / 1
Nav aids · South Pacific Oceanlong running	4	270.5	8	938	1.3× / 3
Spills · North Pacific Ocean	4	63	1	35	0.9× / 4.4
Incidents · Caribbean Sea	4	55	4	41	1.0× / 4
Nav aids · Irish Sea and St. George's Channelsurge	4	54.2	0	—	2.5× / 1.6
Surveys · Gulf of Mexicosurge	4	21.6	1	19	3.3× / 1.2
Exercises · Andaman or Burma Seasurge	4	11.3	1	27	3.3× / 1.2
Derelicts · Indian Ocean	4	11.2	0	—	1.1× / 3.6
Nav aids · Mediterranean Sea - Western Basinsurgelong running	3	140.2	3	365	3.8× / 0.8
Nav aids · North Sea	3	121.6	4	246	0.5× / 6.6
Surveys · Indian Oceansurge	3	112	3	104	3.8× / 0.8
Nav aids · Coral Sea	3	94.1	3	70	0.3× / 8.8
Wrecks · Arabian Seanewlong running	3	80.8	4	615	new / 0
Cable ops · North Pacific Oceansurge	3	72.4	2	81	2.5× / 1.2
Cable ops · South China Seasurge	3	32.9	2	103	3.8× / 0.8
Surveys · Mediterranean Sea - Western Basinsurge	3	22.2	0	—	2.1× / 1.4
Exercises · Japan Seasurge	3	20.1	0	—	7.5× / 0.4
Exercises · Norwegian Sea	3	11.8	1	29	1.9× / 1.6
Derelicts · North Atlantic Ocean	3	9	0	—	1.1× / 2.6
Quakes · Philippine Sea	3	9	0	—	1.1× / 2.8
Derelicts · South Atlantic Ocean	3	9	1	20	0.7× / 4.4
Missiles · South China Seasurge	3	3.4	0	—	7.5× / 0.4
Incidents · Coral Sea	3	0.1	0	—	1.1× / 2.6
Nav aids · Caribbean Sea	2	363.5	12	231	0.8× / 2.6
Exercises · Aegean Sea	2	216.3	7	139	0.2× / 8.4
Surveys · Barentsz Sea	2	122.4	5	136	10× / 0.2
Nav aids · Arabian Sea	2	98.1	3	147	0.7× / 2.8
Surveys · South Pacific Oceanlong running	2	91.7	2	607	10× / 0.2
Spills · Gulf of Mexico	2	52	0	—	0.4× / 5.4
Surveys · Tyrrhenian Sea	2	50.1	2	30	10× / 0.2
Wrecks · South Pacific Ocean	2	46.2	2	61	2.5× / 0.8
Incidents · North Atlantic Ocean	2	31.3	1	40	0.1× / 14.8
Other · Arabian Sea	2	27.6	2	13	5.0× / 0.4
Surveys · Bay of Bengal	2	24	0	—	3.3× / 0.6
Surveys · North Pacific Ocean	2	23	0	—	5.0× / 0.4
Cable ops · Caribbean Sea	2	22.2	1	185	10× / 0.2
Surveys · Ligurian Sea	2	20.4	0	—	2.5× / 0.8
Derelicts · South Pacific Ocean	2	17.8	1	34	1.7× / 1.2
Incidents · Gulf of Mexico	2	17.2	0	—	0.7× / 3
Missiles · Japan Sea	2	16.3	0	—	0.8× / 2.4
Missiles · Barentsz Sea	2	11.3	0	—	0.5× / 4
Other · Black Seanew	2	8.5	1	16	new / 0
Containers · Laccadive Seanew	2	6.7	1	6	new / 0
Exercises · Coral Sea	2	4.1	0	—	1.4× / 1.4
Debris · Indian Ocean	2	3	0	—	1.7× / 1.2
Nav aids · Bass Strait	2	2.9	0	—	1.7× / 1.2
Missiles · South Pacific Ocean	2	2.5	0	—	0.7× / 3
Nav aids · Celtic Sea	2	0.8	0	—	2.5× / 0.8
Nav aids · Strait of Gibraltar	2	0.8	0	—	10× / 0.2
Derelicts · English Channel	2	0.7	0	—	10× / 0.2
Nav aids · North Pacific Oceanlong running	1	202.2	7	668	0.2× / 4.2
Nav aids · Gulf of Mexico	1	172.1	6	177	0.3× / 3.4
Other · Persian Gulf	1	77.1	3	329	5.0× / 0.2
Wrecks · South Atlantic Ocean	1	75.6	3	133	0.8× / 1.2
Nav aids · Mozambique Channel	1	66.1	2	229	1.3× / 0.8
Restricted · South Atlantic Oceanlong running	1	62.8	2	515	2.5× / 0.4
Derelicts · Arabian Sealong running	1	62	2	493	5.0× / 0.2
Nav aids · Bay of Bengal	1	55.4	2	355	2.5× / 0.4
Nav aids · Mediterranean Sea - Eastern Basin	1	52.2	2	298	5.0× / 0.2
Other · North Pacific Ocean	1	46.7	1	59	0.8× / 1.2
Nav aids · English Channel	1	40	1	50	0.3× / 3.6
Nav aids · Indian Ocean	1	39.8	2	51	0.6× / 1.8
Surveys · Norwegian Sea	1	37.3	1	34	0.5× / 2.2
Derelicts · Caribbean Sea	1	34	1	62	1.0× / 1
Exercises · Laccadive Sea	1	33.6	0	—	0.6× / 1.8
Nav aids · Tasman Sea	1	32	2	94	0.7× / 1.4
Surveys · Mozambique Channel	1	31	1	42	2.5× / 0.4
Surveys · Tasman Sea	1	30.8	1	53	5.0× / 0.2
Other · Japan Sea	1	29.3	0	—	new / 0
Cable ops · Norwegian Sea	1	25.2	1	25	0.7× / 1.4
Cable ops · Philippine Sea	1	22.9	0	—	2.5× / 0.4
Spills · Chukchi Sea	1	14	0	—	new / 0
Wrecks · Laccadive Sea	1	12.6	1	12	new / 0
Incidents · Andaman or Burma Sea	1	10.8	0	—	5.0× / 0.2
Exercises · Barentsz Sea	1	9.5	0	—	0.5× / 2.2
Cable ops · South Atlantic Ocean	1	9	0	—	1.7× / 0.6
Other · North Atlantic Ocean	1	8.6	0	—	0.5× / 2.2
Missiles · Baffin Bay	1	8.3	0	—	5.0× / 0.2
Cable ops · Indian Ocean	1	7.9	1	7	1.7× / 0.6
Cable ops · Timor Sea	1	7.9	0	—	new / 0
Exercises · Celtic Sea	1	7.3	0	—	new / 0
Piracy · Gulf of Guinea	1	7	0	—	0.3× / 3.8
Piracy · Singapore Strait	1	7	0	—	5.0× / 0.2
Cable ops · Eastern China Sea	1	6	0	—	1.0× / 1
Missiles · Arctic Ocean	1	5.6	0	—	new / 0
Missiles · Norwegian Sea	1	4.3	0	—	0.7× / 1.4
Missiles · Laccadive Sea	1	4	0	—	1.7× / 0.6
Structures · South Atlantic Ocean	1	4	0	—	new / 0
Debris · Arabian Sea	1	3	0	—	5.0× / 0.2
Derelicts · Bay of Bengal	1	3	0	—	1.0× / 1
Debris · Coral Sea	1	3	0	—	new / 0
Quakes · Eastern China Sea	1	3	0	—	1.7× / 0.6
Derelicts · Mediterranean Sea - Eastern Basin	1	3	0	—	1.0× / 1
Debris · North Atlantic Ocean	1	3	0	—	1.0× / 1
Quakes · North Atlantic Ocean	1	3	0	—	1.7× / 0.6
Derelicts · Philippine Sea	1	3	0	—	new / 0
Other · South Atlantic Ocean	1	3	0	—	new / 0
Debris · South Pacific Ocean	1	3	0	—	1.0× / 1
Exercises · Mediterranean Sea - Eastern Basin	1	1.7	0	—	0.1× / 18.8
Exercises · Tyrrhenian Sea	1	1.6	0	—	new / 0
Missiles · Gulf of Mexico	1	1.5	0	—	new / 0
Exercises · Mediterranean Sea - Western Basin	1	1.1	0	—	0.6× / 1.8
Nav aids · Tyrrhenian Sea	1	1.1	0	—	5.0× / 0.2
Other · South China Sea	1	0.8	0	—	new / 0
Exercises · Adriatic Sea	1	0.4	1	0	new / 0
Derelicts · Java Sea	1	0.4	0	—	new / 0
Incidents · Bass Strait	1	0.2	0	—	5.0× / 0.2
Incidents · Malacca Strait	1	0.1	0	—	5.0× / 0.2
Incidents · Timor Sea	1	0.1	0	—	0.7× / 1.4
Wrecks · South China Sealong running	0	279	9	834	0.0× / 1
Wrecks · Persian Gulflong running	0	258.7	8	532	0.0× / 0.4
Surveys · Black Sea	0	118.1	3	87	0.0× / 1
Exercises · Ionian Sea	0	93	3	139	— / 0
Surveys · Mediterranean Sea - Eastern Basin	0	80	2	154	0.0× / 4.2
Nav aids · Andaman or Burma Sea	0	62	2	147	0.0× / 0.6
Surveys · Arctic Ocean	0	62	2	224	— / 0
Other · Gulf of Mexico	0	62	2	140	— / 0
Wrecks · Inner Seas off the West Coast of Scotland	0	62	2	234	— / 0
Wrecks · North Pacific Oceanlong running	0	62	2	788	— / 0
Ordnance · North Sealong running	0	62	2	595	0.0× / 3.4
Volcanic · Philippine Sea	0	62	2	164	— / 0
Cable ops · Arabian Sea	0	61.7	1	133	0.0× / 1.2
Cable ops · Aegean Sea	0	31	1	168	0.0× / 0.6
Missiles · Aegean Sea	0	31	1	139	0.0× / 0.8
Other · Arafura Sea	0	31	1	54	0.0× / 0.6
Surveys · Bering Sea	0	31	1	222	— / 0
Cable ops · Black Sea	0	31	1	125	0.0× / 0.2
Nav aids · Black Sea	0	31	1	46	— / 0
Volcanic · Caribbean Sea	0	31	1	49	— / 0
Wrecks · Caribbean Sea	0	31	1	69	0.0× / 0.2
Other · Coral Sea	0	31	1	69	0.0× / 0.4
Wrecks · English Channel	0	31	1	143	0.0× / 0.2
Nav aids · Gulf of California	0	31	1	104	— / 0
Nav aids · Gulf of Thailandlong running	0	31	1	592	0.0× / 0.2
Wrecks · Japan Sea	0	31	1	130	— / 0
Incidents · Java Sealong running	0	31	1	448	0.0× / 0.8
Other · Mediterranean Sea - Eastern Basin	0	31	1	249	0.0× / 0.6
Other · Mozambique Channel	0	31	1	42	— / 0
Volcanic · Mozambique Channellong running	0	31	1	606	— / 0
Wrecks · North Sea	0	31	1	31	0.0× / 1
Cable ops · Persian Gulf	0	31	1	190	0.0× / 0.6
Nav aids · Persian Gulflong running	0	31	1	411	0.0× / 0.2
Mines · Persian Gulf	0	31	1	148	— / 0
Restricted · Persian Gulflong running	0	31	1	775	— / 0
Wrecks · Red Sealong running	0	31	1	534	— / 0
Exercises · South China Sea	0	31	1	67	0.0× / 1.8
Structures · South China Sealong running	0	31	1	553	0.0× / 0.2
Surveys · South China Sealong running	0	31	1	627	0.0× / 1
Nav aids · Norwegian Sea	0	27.4	0	—	0.0× / 0.2
Nav aids · Laccadive Sea	0	16.4	0	—	0.0× / 1
Nav aids · Arafura Sea	0	12	0	—	0.0× / 1
Other · Bering Sea	0	5.8	0	—	— / 0
Surveys · Irish Sea and St. George's Channel	0	4.5	0	—	0.0× / 0.2
Debris · Bay of Bengal	0	2.4	0	—	0.0× / 0.2
Exercises · Yellow Sea	0	1.6	0	—	0.0× / 7.6
Surveys · Great Australian Bight	0	0.3	0	—	— / 0
Exercises · Bering Sea	0	0.2	0	—	0.0× / 1
Spills · The Coastal Waters of Southeast Alaska and British Columbia	0	0	0	—	0.0× / 0.6

Cite: seahazards.com Sea Ledger, 2021-05, 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.