Travelling in Georgia you get used to checking the daily weather forecast. Georgia in summer is hot and humid from the Black Sea and has high mountains: All the ingredients you need for subtropical (= heavy) rains and heavy thunderstorms, specifically at the coast. In Batumi it rains roughly 2.100mm each year. This has created a unique subtropical landscape along the coast, breaking down into two types of location as the site's name suggests:
Flat wetlands around Poti.
Subtropical rainforests in the mountains north-east of Batumi. Funnily, while the Georgians made a huge effort to give each wetland a separate location, they grouped the two rainforest National Parks into one location; a bit misleading.
Of the two types, the mountainous rainforests are the true gem. Exiting the car in Mitrala National Park, we immediately felt the air soaked with water like in a greenhouse. We hiked to the waterfall and were impressed with the scenery.
The wetlands meanwhile are rather mundane and pale in comparison to e.g., the Everglades or the Danube Delta on the western shore of the Black Sea. Our initial plan had been to visit the day prior, but thunderstorms that day meant that no boat was going to the national park, so we came back the next day.
Getting There
Stanislaw has a nice rundown of all the components and their respective accessibility. Accessible for tourists are:
Kolkheti National Park: Boat tours can be arranged at the visitor centre in Poti. Call the visitor centre ahead to make a reservation, especially in high season. Unlike Zoe seems to suggest, Lake Paliastomi is pretty large, so I don't think you can count this without the boat ride. Only option for that would be Gringoleti component to the South of the lake which is fenced and really doesn't offer any views either.
Mitrala National Park: Taxi (gotrip.ge) from Batumi and hike. The cable car across the river is free nowadays.
Kintrishi Nature Reserve: Taxi (gotrip.ge) from coast (Batumi) and hike.
Figuring out where to base ourselves for the visit took several days. Batumi felt too far South and too touristy. Initially, Poti seemed like the best option, but it is a rundown place (agreeing with Zoe). We explored several other options along the Black Sea coast, before settling on Batumi. I think this was the correct call as it's really the only nice town along the Georgian coast and connections are best.
We arrived by mashrukta from Mestia (6h). The next day we arranged a driver (gotrip.ge) and travelled via Mitrala National Park, Kolkheti National Park and Vani (T) to Kutaisi.
While You Are There
Batumi has a little old town and a long coastline lined with large modern hotels and casinos. The beach itself is made up of large stones and it rains heavily all year; not sure I would plan a summer vacation here. If you want to explore mountain scenery the Adjara mountains on the Turkish border are said to be nice. Not to be missed is the Batumi Botanical Garden.