drainage holes, as well as horizontal and vertical cracks and fissures in the rock, as the water percolates downwards, creating distinctive surface features such as vertical fluting (karren), solution pans, limestone pavement and sinkholes (doline), while beneath the surface it leads to the formation of an extensive network of caves and underground drainage channels, with all rainwater rapidly disappearing underground.
Collapses in the roof of these subterranean voids leads to the formation of larger sinkholes and cenotes. (Most of the deeper caves and sinkholes in Croatia are on the mainland, and some of these are extremely deep – Lukina jama on Velebit is among the 15 deepest sinkholes in the world.) Polje – large, level-floored depressions up to several kilometres in size, where a thin layer of alluvial soil has gradually accumulated – often form the only suitable areas for growing vegetables and the cultivation of crops.
Many of these features will be encountered while walking on the islands – for example Jama Komoračišće, a prominent sinkhole on Kom, Korčula (Walk 27), and limestone pavement on Šćah, Ugljan (Walk 15), to name but two. On the island of Rab a number of such karst and other geological features are highlighted on marked geological trails (Walk 7).
The island of Susak (and part of Unije) is unusual in being composed largely of sand and loess laid over a limestone base; while the quarries of Brač have long been famed for their white marble, much prized by sculptors and used to build Diocletian’s palace in Split during antiquity and, more recently, part of the White House in Washington DC.
Climate
The Croatian coast and islands experience a Mediterranean climate, and this is distinct and separate from the inland continental climate, which is significantly colder during the winter. The islands are protected from this colder climate by the mountain barrier of the coastal ranges (the Dinaric Alps).
Evening light on the east slopes of Sv Vid, seen from Pag town (Walks 13 and 14)
Summers on the coast and islands are hot and dry, with average mean temperatures of between 21°C and 22°C on the northern and central Dalmatian islands in June and September, and average mean temperatures of between 24°C and 25°C for the same area in July and August. At least half the days in July and August reach 30°C or above, although the highest temperatures recorded are not above 37°C–38°C. Even outside the summer months it is a balmy 18°C and 17°C in October and May respectively, and 14°C in April. Expect temperatures to be slightly higher in the south (Korčula, Dubrovnik) and very slightly cooler further north (Cres, Rijeka) – although these differences may be minimal. Hvar is supposed to have the most hours of sunshine on the Croatian Adriatic – around 2715 per year – with most other islands in central Dalmatia not far behind. Sea-water temperatures in central Dalmatia are usually around 22°C in June and September, and up above 24°C in July and August – most Croats would consider sea-water temperatures of anything less than 20°C decidedly chilly.
Whereas the heat can frequently become intense in early August on the mainland coast and in cities such as Split and Dubrovnik, summer temperatures on the islands are generally moderated by a light breeze, making them significantly more pleasant. These general observations do not hold true on islands with less vegetation, such as Pag or Goli otok (‘naked island’), where the heat during the summer months can be well and truly fierce.
Winters on the coast and islands are relatively mild, although frequently rainy (with less rain on the islands than the coast). January is the coldest month, with an average mean temperature of around 8.5°C on northern and central Dalmatian islands. November tends to be the wettest month. Snow is rare in the mainland coastal area (not so the mountains just inland from the coast, which see significant snowfall during the winter months) and rarer still on the islands – even Split and Dubrovnik are unlikely to see more than one day of snow, on average, in January.
Several winds can buffet the Croatian coast and islands at any time of year, the strongest (and most disruptive) of which is the bura – a cold northeasterly, which descends upon the Adriatic from the cols and high passes of Velebit in gusts which frequently reach gale force. The Venetian traveller Alberto Abbé Fortis, writing in the 18th century, even claimed that on occasions the bura would pick up young children and dash them against the walls of houses, and throw down horses loaded with salt. There is a saying in Croatia that the bura is born in Lika (the region behind the Velebit mountains), lives on Velebit and dies on the sea – but you can expect it to give the eastern coasts of Krk, Rab, Pag and some other islands a pretty good battering, too. When the bura really does blow, expect choppy (and cooler) seas, possible disruption to ferry and catamaran services, and possible closures of bridges to traffic (including buses) on the main coastal highway.
Trees bent by the bura wind, on the rocky northeast coast of Rab (Walk 6)
Other winds include the jugo, a moderate southerly (jug meaning ‘south’) that typically brings cloud and rain to the coastal mountains and is traditionally associated with bad temper and ill health. (In the Republic of Dubrovnik during the Middle Ages, crimes committed when the jugo was blowing generally earned a more lenient sentence for their perpetrator, following the belief that the wind had, at least partially, driven them to commit the crime or induced their fit of rage.) The maestral is a brisk sea breeze that tends to blow from the morning to the early afternoon; the široko is a warm, dry southeasterly from north Africa, roughly equivalent to the sirocco in other parts of the Mediterranean.
When to visit
On balance, the best time to visit Croatia’s islands is between April and October, with May, June and September being the best for walking, and July/August being the hottest and busiest (most Croatians take their holidays on the Croatian coast in early August). Wildflowers will be at their most impressive in June. Many hotels and private rooms close during the winter, although prices will be lower than in high season at those which do remain open, and competition for rooms much less. Some ferries operate a reduced service outside the summer months. On public holidays (see ‘Croatian national holidays’ below) expect shops to be closed and public transport to be considerably restricted.
Wildlife
Croatia has an incredibly rich biodiversity for a country its size, with over 38,000 known species of plants and animals, including around 1000 which are endemic, and many species that are threatened or endangered. The Croatian islands are particularly interesting for the profusion of reptiles and invertebrates that can be seen, and for their extraordinarily rich plant life, while the surrounding waters of the Adriatic are inhabited by a wealth of marine life.
Mammals
Mammals including Red and Roe deer, Wild pig and Fox can be found on various islands on the Croatian Adriatic, along with smaller species such as Red squirrel, Pine marten and Common dormouse. There are several species of bat (at least five species on Lastovo alone), including Greater and Mediterranean horseshoe bat, Savi’s pipistrelle and Long-fingered bat (the latter classified as vulnerable on the International Union for Conservation of Nature (IUCN) Red List). Mouflon (wild sheep, ancestor of modern domestic breeds) can be seen on Dugi otok and Lastovo, having been introduced for hunting in the 19th century, and a few of the islands are home to an elusive and little-known carnivore, the European jackal (Canis aureus, also known as the Golden jackal). None of the other large carnivores present in small numbers on the Croatian mainland – Brown bear, Grey wolf and Lynx – are found on the islands. The island of Mljet is conspicuous as the only place in Europe where the Indian grey mongoose is found in the wild, having been introduced in the early 20th century to exterminate the island’s burgeoning native population of snakes. Incidentally, Croatia’s currency (the kuna) is named after the Pine marten – kuna in Croatian – the pelts of which were used as a unit of trade and measure of currency in the Middle Ages.
Istrian cattle at the edge of Unijsko polje, on the island of Unije (Walk 12)
Domesticated