There are fairly modern and air-con trains every hour or more frequently during the rush hours to and from Adana and Tarsus. The journey time is between 45-80 minutes, depending on the number of stops. The price is 5,5 TL for one way and 9 TL for a roundtrip. There is an option to buy an unlimited card for 110 TL, valid for a month. The price is 80 TL for students. You should buy the ticket before you enter the train, otherwise the price is doubled.
The only international train link is from Syrian city of Aleppo, from where weekly trains depart at 3AM on Fridays, and arriving in Mersin about nine hours later, at 12:18PM. They cost € 14 pp. (This train is halted indefinitely for a while, so it is wise to check before planning the trip)
There is a bus station in eastern part of the city. There are city buses running between the city center and the bus station. Usually each bus company has its own shuttles running between city center, western (coastal part) and the bus station. From the bus station there are buses to almost every city in Turkey and to small cities and villages in Cilician Mountains (the rest of Mersin Province), including buses from Gaziantep (5hrs, 25TL) and Silifke (2hrs 10TL) 
Buy very high quality leather jackets from the bazaar just beside Holly Mosque (local name Ulu Cami). Don't forget to bargain, and after bargaining for 15 minutes, you might be able to buy leather jacket for half price. There is an antique store behind the Mersin Hotel specialised on praying beads. The price of praying beads range from 10 TL to 5000 TL and higher and it is hard to evaluate the price, the 50TL-100TL range is adequate for a souvenir. Dösim Store is an excellent trustworhty place to buy a asouvenir, the prices are fixed (no bargaining) and fairly cheaper than other stores. Since it is a public institution, the products are authentic and usually comes with a certificate in English. Dösim store is beside the Atatürk's House in Mersin.
Tantuni, finely minced fried meat and onion wrap, is one of the most famous food in this region. Don't leave the city without tasting it. In the center of the city, you will see several small local restaurants with this special fantastic food.
Haslets are very common ingredients of the food in Mersin. There are dishes made with intestines, lung, liver, kidneys, stomach, brain. Even though there are restaurants serving this food all through out the day, this type of food can be found easily late at nights. Especially soups with inner organs are drank late at night after consumption of alcohol.
Cezerye is a mix made of carrots and fig and lots of spices may also include nuts depending on where you buy it from.
Kerebic is dessert unique to this area. It is a dough filled with pistachios and served with vegetarian cream on top of it.
Künefe is also another dessert completely unique to the arabic influented areas. Its oven baked shredded pastry with salt-free cheese filling in thick syrup. Although its really requires a developed taste, it carries the spirit of the vicinity
Şalgam can be found on every street in Mersin even though it is a drink from Adana. Good examples of local brands are Serafressh (with double s) and Turnib (with b, not p). Since the cities in Çukurova all have similar cuisines taste of Salgam doesn't differ that much.
In the past there were many Boyan (licorice drink) sellers in the city center. Such drink still exists but cannot be found easily.
Kaynar is another local drink, generally served to celebrate a newborn. It is usually served hot with cinnamon and walnut. The ingredients of kaynar can be found in some stores and can be a cheap exotic gift.
There are many hotels in the city, but one of the best ones is Sultasa Hotel. It is a kind of in the city center. The entrance fee for this place is 35YTL excluding accommodation. For accommodation, you should pay 80YTL more.