Tuapse is a city in Krasnodar Krai.
An important Russian port at the Black Sea and the closest neighbour town bordering Greater Sochi, Tuapse is mostly industrial and transport hub, attracting fewer number of tourists, than other Russian Black Sea coastal locations. But anyway, Tuapse is good for a single-day visit.
Any elektrichka or long-distance train from Sochi stops in Tuapse, the frequent bus/marshrutka connection is also available. Expect 2 - 2,5 hours for one-way trip from Central Sochi.
There are several very scenic cliffs around, the top of those is Kiselev's Rock, a 46 meter upright cliff breaking down into the sea.
Quite many ancient cultural remains, such as table-stones, are also located around Tuapse.