A dozen kilometres northwest of Kutaisi, Tskaltubo is a spa where mildly radioactive water at an average 15°C is used to treat arthritis, rheumatism, polio and fertility problems. In Soviet times none of the hotels in Kutaisi were open to Westerners, and they had to stay out here; the hotels and sanatoria were taken over by refugees from Abkhazia, so now you have to stay in Kutaisi and come here for a day trip.
Marshrutka 22 runs from the junction of Chavchavadze and Rustaveli, near the bus station, passing through an area of low pines where wild camping would be possible. After 15 minutes you'll enter the spa, passing the station (served by a few trains a day from Kutaisi II) and a large park dotted with pines that's very attractive to the south but more unkempt as you get to the centre. The town is spacious and fairly modern with little to see; you can ask to try the waters at the big Stalinesque sanatorium.
Of more interest to cavers is the Kumistavi Cave, 7km from Tskaltubo, having been found only in 1983. It's 1.5km long and 145m deep, with 15 chambers, and a river (with waterfalls) runs through it; there are also 10-12 species of bats living here.