Finnish company Nordic Urban is planning to build the outdoor, floating swimming pool and sauna facility within two of the listed graving docks.
The second attraction planned is a 90m high balloon ride with a rotating viewing platform on unused land close to the Red Dragon Centre.
The platform would give panoramic views of the city and the waterfront of up to 20 miles and is developer Skyview’s first UK-based ride.
Cllr Russell Goodway, Cabinet Member for Investment and Development, said: “This administration has been clear from the outset about our commitment to rejuvenate Cardiff Bay.
“It’s our intention to transform this historic part of Cardiff into a leading UK destination for leisure, culture and tourism, increasing visitors and, just as importantly, creating more jobs and opportunities for local people.
“Both developments will be privately funded and the Council’s only contribution is to make the land available.”