Boat trip is a along the coast which takes 2 hours, on a boat named Samsunum ("my Samsun").
Fishing is very funny and good activity gives you pleasure in the Black Sea for its rich fish varieties.
If you are interested in arts, you will find a thing or two that you might like. There is a very large and interesting opera building with weekly shows.
Two festivals are celebrated annually in the city. Some competitions are held during the Bike Festival. On the other hand, concerts of popular singers are to be found during the Festival of OMÜ (Ondokuz Mayıs Üniversitesi, one of the local universities). Both festivals are usually celebrated around the end of June.
For a city of half a million there are very few foreigners, so most people will be happy to chat if you want to. Try the sea front, parks or outdoor cafes. No need to feel lonely if you are travelling on your own. Just ask one of the many English language schools if their students need any conversation practice - especially if you are a native English speaker they will welcome you with open arms.
There is a paintball ground in the locality known as Körfez, somewhat far from city centre.
Go Karting. There is a go kart course in Batıpark (West Park)
Water Skiing is a water skiiers are towed around by an overhead circuit, near Dogupark (East Park) in summer.