The island is part of a chain of mountains from which it became separated after earthquakes and subsidence that occurred in ancient times. These mountains include Kalymnos and Kappari which are separated by an underwater chasm c. 70 m (40 fathoms deep), as well as the volcano of Nisyros and the surrounding islands.
There is a wide variety of rocks in Kos which is related to its geographical formation. Prominent among these are the Quaternary layers in which the fossil remains of mammals such as horses, hippopotami and elephants have been found. The fossilised molar of an elephant of gigantic proportions was presented to the Paleontology Museum of the University of Athens.
The shores of Kos Island are washed by the waters of the Aegean Sea. Its coastline is 112 km long and is caressed by long immaculate beaches, leading to its main industry being tourism. Farming is the principal occupation of many of the island's inhabitants, with their main crops being grapes, almonds, figs, olives, and tomatoes, along with wheat and corn. Cos lettuce may be grown here, but the name is unrelated.
The main villages of Kos island are Kos Town, Kardamena, Kefalos, Tingaki, Antimachia, Mastihari, Marmari and Pyli. Smaller ones are Zia, Zipari, Platani, Lagoudi and Asfendiou.
The island of Kos is part of the Dodecanese. It is the third largest of this group of islands and the second most popular and touristy island after Rhodes. It is located between Kalymnos and Nysiros. It is very well organised and has everything in terms of tourism infrastructure.
From May till October charter airlines fly directly to Kos from many European airports.
It is also possible to take a ferry from Turkish coasts, Bodrum and Datça. To Bodrum there is the faster Hydrofoil boat  (from €30 one-way, passenger only) or the slower ferry operated by the Bodrum Ferryboat Association (passenger/car/caravan: €28/100/200)
It is a fairly small island and there is every now and then a public bus going to every part of the island. From the airport, there is a public bus going to Kos town via Mastichari. Departure times can be found at the bus stops.
Depending on the season, there is many passenger ferries leaving for various neighboring islands. The main ferry to Kalymnos leaves from Mastichari. In high season, there are also daily ferries to Nisyros leaving from Kardamena.
There is plenty of taxis on the island. From the airport they will charge at least €15, even if you just go the Mastichari, which is only 5 minutes away.
By rental scooter
Scooters, ATVs and cars can be hired from many places. If you hire a scooter for several days, rent can be as low as 10€ a day.
- Tree of Hippocrates. The current tree is only about 500 years old, but may possibly be a descendant of the original tree from 2400 years ago. According to the legend, Hippocrates of Kos taught his pupils the art of medicine under the platane tree.
Relax on the beach, wind- and kitesurfing.
The island of Kos is a top yacht charter destination in Greece. You can start your sailing experience from Kos and follow any possible route to other magnificent islands. The marina of Kos is located at the old harbour and is known worldwide since it has been available to skippers and yachting enthusiasts for over a decade. It has been described as one of the hottest cruising areas in Europe as it fulfills every need for any type of boat, such as: fuel/petrol, speedboats, WC-showers, bilge & sewage pump out, waste disposal and many more.
- Istion Yachting (Yacht Charter in Kos), G.Papandreou Avenue, Kos Marina, 85300, ☎ +30 22420 22195. Visitors and tourists can find a wide selection of yachts and catamarans and suggestions about sailing itineraries from Kos to all the surrounding islands and Turkey coasts.
If you're on a budget, there is pita gyros for € 2,5 sold by most restaurants (some for 2€)
- Mummy's Cooking Restaurant (Evdokia), 13 Bouboulinas, Kos Towns (near Dolphin Square)). Tavern with traditional Greek food. Let mummy's son help you decide what to order and be surprised how good it all tastes. Reasonable prices, f.e. Moussaka 7€.
- Restaurant Alexandros, Irakleous, Kos Town (city center, near church with bright blue, illuminated cross on the steeple, walk up the stairs). Tavern with traditional Greek food. Almost every night full, but just keep trying if there is a place free. It is worth it. Reasonable prices, f.e. Moussaka 6€.
- Aegean Houses Hotel (Hotel in Kos), Ethelonton Palaion Polemiston, Lambi, Kos, ☎ +30 22420 48410. Check-in: 14:00, check-out: 12:00. One of the most beautiful Kos hotels, Aegean Houses is a combination of traditional and modern architecture, 300 metres from the sandy beach.
- Ampavris Hotel (Kos Town), ☎ +30 22420 25780. A family-run hotel, located in Ampavris area on a small hill just a short distance walk from Kos Town with nice view.
- Artemis Hotel (Lambi, Kos Town). Artemis hotel apartments is located in Lambi area, just 1km from the harbour and Kos town center. The most popular beach of Kos island is just 150m away.
- Gaia Hotels (Kos City, Mastichari, Tigaki), ☎ +30 22420 25804. A hotel chain with four resorts hotels located in Kos.
- Katras Hotel Apartments (Tigaki), ☎ +30 22420 68238. It is located in Tigaki and consists of 55 sunny rooms.
- Leonidas Hotel and Studios, Sintagmatos Dodekanision st., (Kos Town), ☎ +30 2242026921. Leonidas Hotel and Studios is the most popular 2 star hotel and the first discount hotel on Kos island. Price for a Double Room from 15€/night.
- Michelangelo Resort & Spa Hotel, Agios Fokas, Kos 85300, ☎ +30 2242045810, fax: +30 2242045825, e-mail: firstname.lastname@example.org. A modern hotel with rooms and suites with views to the sea and gardens.
- Sunny Days Hotel (Tigaki). It is situated at Tigaki of Kos 500 meters from the beach.
- Nissia Kamares Hotel Apartments, Kardamena (Close to the church), ☎ +30 6936207428. Check-in: 12:00, check-out: 11:00. Built in a very distinctive traditional Greek island style, Nissia Kamares Hotel Apartments comprises 38 studios and apartments on two floors. Varies.
Kos is a very safe area and should not be a major problem for travellers. Just take normal precautions.