Which seas and ferry crossings are roughest in June

Of the 68 seas and ferry routes on this site, 11 sit at rough or roughest in June and 42 are calm. 10 are at the hardest level they reach in any month of the year. Against May, 12 step up a level and 12 step down.

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Every water ranked for June

Each level below is the one that water carries for June on its own page. It describes the typical pattern of the month, not a forecast for your sailing date. A water marked as its own worst is at the hardest level it reaches in any month of the year.

Roughest in June: 6 of 68

This water at its hardest. These are the months its reputation comes from, and the ones passengers write about afterwards.

Seas and ferry routes rated roughest in June
Sea or route	What drives it	Rest of its year
Bass StraitSea area, Southern Australia. Worst level of its year.	Ocean swell shortening over a 60 m shelf	high
Drake PassageSea area, Southern Ocean. Worst level of its year.	No land to stop wind, swell or current	very high
Foveaux StraitSea area, Southern New Zealand. Worst level of its year.	Roaring Forties swell over a shallow seaway	very high
Geelong to Devonport (Spirit of Tasmania)Ferry route, Australia and New Zealand. Worst level of its year.	Ocean swell shortening over a 60 m shelf	high
Great Australian BightSea area, Southern Australia. Worst level of its year.	Southern Ocean swell with unlimited fetch	high
Tasman SeaSea area, South-west Pacific. Worst level of its year.	2,000 km of unbroken westerly fetch	high

Rough in June: 5 of 68

The difficult half of this water's year. Calm days still happen, but bad ones are common enough to plan around.

Seas and ferry routes rated rough in June
Sea or route	What drives it	Rest of its year
Bali (Padangbai) to Gili TrawanganFerry route, Asia. Worst level of its year.	Deep strait currents under small fast boats	high
Cook StraitSea area, New Zealand	Wind against a 5-knot tidal stream	high
Dar es Salaam to ZanzibarFerry route, Africa. Worst level of its year.	Indian Ocean swell across an open channel	moderate
Hong Kong to MacauFerry route, Asia. Worst level of its year.	An estuary that opens to the South China Sea	moderate
Wellington to PictonFerry route, Australia and New Zealand	75 exposed minutes in a wind funnel	high

Mixed in June: 15 of 68

It depends on the week. Settled weather gives an easy passage here, an approaching front gives an uncomfortable one.

Seas and ferry routes rated mixed in June
Sea or route	What drives it	Rest of its year
Aegean SeaSea area, Eastern Mediterranean	Summer meltemi funnelled down the Aegean	moderate
Bar Harbor to Yarmouth (The CAT)Ferry route, North America	Open Gulf of Maine at catamaran speed	moderate
Buenos Aires to Colonia del SacramentoFerry route, Caribbean and Latin America. Worst level of its year.	A shallow brown-water estuary with one bad wind	low
Gulf of LionSea area, Western Mediterranean	Mistral funnelled down the Rhône valley	high
Hirtshals to TorshavnFerry route, Northern Europe	A day and a half into the open North Atlantic	high
Hyannis to NantucketFerry route, North America	Shallow sound chop under fast catamarans	moderate
Mediterranean SeaSea area, Mediterranean	Mistral in the west, meltemi in the Aegean	moderate
Mona PassageSea area, Caribbean	Tidal current forced over shallow banks	moderate
Mozambique ChannelSea area, South-west Indian Ocean	Cyclone corridor feeding the Agulhas Current	high
Mykonos to SantoriniFerry route, Southern Europe	Beam-on to the meltemi in small fast craft	high
Pentland FirthSea area, Northern Scotland	Tidal races, not wind-driven waves	very high
Penzance to St Mary's (Isles of Scilly)Ferry route, UK and Ireland	Open Atlantic swell met by a flat-bottomed hull	high
Piraeus to Heraklion (Crete)Ferry route, Southern Europe	The full meltemi fetch, slept through on big ships	moderate
Scrabster to StromnessFerry route, UK and Ireland	Tidal races, not wind-driven waves	very high
Strait of GibraltarSea area, Spain and Morocco	Wind funneled between two mountain ranges	moderate

Calm in June: 42 of 68

The settled end of this water's year, when most passages pass without much motion worth noticing.

Seas and ferry routes rated calm in June
Sea or route	What drives it	Rest of its year
Aberdeen to LerwickFerry route, UK and Ireland	216 miles up the open northern North Sea	high
Adriatic SeaSea area, Central Mediterranean	Katabatic bora gusts off the Dinaric Alps	moderate
Baltic SeaSea area, Northern Europe	Short steep chop, no ocean swell	moderate
Barcelona to Palma de MallorcaFerry route, Southern Europe	Tramontana and mistral chop on an open crossing	moderate
Bay of BiscaySea area, North-east Atlantic	Atlantic swell over a shoaling shelf	high
Busan to Hakata (Fukuoka)Ferry route, Asia	The overnight strait, after the fast craft era	moderate
Cabot StraitSea area, Atlantic Canada	Atlantic storm track across an open gulf mouth	high
Cairnryan to BelfastFerry route, UK and Ireland	Atlantic weather funnelled through the North Channel	moderate
Cape May to LewesFerry route, North America	Where Atlantic swell meets the estuary	moderate
Caribbean SeaSea area, Caribbean	Trade winds, winter surges and hurricane season	moderate
Dover to CalaisFerry route, UK and Ireland	Shallow strait, wind against tide	moderate
English ChannelSea area, North-west Europe	Shallow strait, wind against tide	moderate
Fort Myers Beach to Key West (Key West Express)Ferry route, North America	A long open-Gulf run at speed	moderate
Gulf of AlaskaSea area, North Pacific	Aleutian Low storms, no island shelter	high
Gulf of MexicoSea area, North America	Winter northers behind cold fronts	moderate
Harwich to Hook of HollandFerry route, UK and Ireland	The shallowest water on the North Sea ferry map	high
Helsinki to TallinnFerry route, Northern Europe	A short hop on outsized ships	low
Holyhead to DublinFerry route, UK and Ireland	Wind against strong tidal streams	moderate
Hull to RotterdamFerry route, UK and Ireland	Overnight across the shallow southern basin	high
Inside PassageSea area, North Pacific	Island shelter, except at its open crossings	moderate
Irish SeaSea area, British Isles	Wind against strong tidal streams	moderate
Korea StraitSea area, East Asia	Monsoon chop over a shallow shelf	moderate
Long Beach to Catalina IslandFerry route, North America	Pacific ground swell under fast hulls	moderate
Naples to CapriFerry route, Southern Europe	Small fast hulls on an open bay approach	moderate
Newcastle to AmsterdamFerry route, UK and Ireland	A full night across the open middle	high
North SeaSea area, North-west Europe	Shallow basin, short steep wind chop	high
North Sydney to Port aux BasquesFerry route, North America	The Atlantic storm track's ferry crossing	high
Oslo to KielFerry route, Northern Europe	Big ships, one open strait in the middle	moderate
Playa del Carmen to CozumelFerry route, Caribbean and Latin America	Wind against the Yucatan current	moderate
Plymouth to RoscoffFerry route, UK and Ireland	The Channel's open Atlantic doorway	moderate
Portsmouth to BilbaoFerry route, UK and Ireland	A long offshore middle over open Biscay	high
Portsmouth to SantanderFerry route, UK and Ireland	Atlantic swell over a shoaling shelf	high
Salish SeaSea area, North Pacific	Mountain-sheltered basins, one strait open to the Pacific	moderate
Sea of JapanSea area, East Asia	Winter monsoon over a long open fetch	high
Seattle to Bainbridge IslandFerry route, North America	The sheltered sound's flagship commute	low
SkagerrakSea area, Scandinavia	North Sea swell funneled into a narrowing strait	moderate
Split to HvarFerry route, Southern Europe	Island-sheltered channel, bora-day exception	moderate
Stockholm to HelsinkiFerry route, Northern Europe	Archipelago shelter, one open Baltic gap	moderate
Stockholm to TallinnFerry route, Northern Europe	The open Baltic Proper in the middle of the night	moderate
The MinchSea area, North-west Scotland	Atlantic swell down an open northern door	moderate
Turku to StockholmFerry route, Northern Europe	One of Europe's calmest long ferry rides	low
Vancouver (Tsawwassen) to Victoria (Swartz Bay)Ferry route, North America	Open strait first, island maze after	low

How June compares with the months either side

Coming out of May, 12 of these waters move up a level and 12 move down. The rest hold where they were. Roughness does not switch on in one month: most of these waters shift a step at a time, which is why the shoulder months either side of a bad season are often the useful booking window.

The two hemispheres also run opposite. A month at the calm end of the year in the North Atlantic is the hard end of it in the Southern Ocean, so a single month page holds both a list of waters to avoid and a list to book.

Previous month

Roughest water in May

Next month

Roughest water in July

Sailing somewhere on this list in June?

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