buoyant

Having buoyancy; able to float.

And of course, in order to understand the Earth's past and how it got to where it now is, it is important to have a basic knowledge of plate tectonics, which explains how the planet's continental and oceanic crusts are part of the lithospheric plates that are buoyant and ride upon the highly viscous asthenosphere.

Lighthearted and lively.

I’m in a buoyant mood.

There was no delirium when he awoke in the morning. Instead, there was only a feeling of buoyant health. In fact, Dave Hanson had never felt that good in his life—or his former life. He reconsidered his belief that there was no delirium, wondering if the feeling were not itself a form of hallucination.

Involving or engaged in much successful trade or activity. (of an economy, business etc.)

[...] the accelerated, high-frequency East Coast express timetable, operating this year in a buoyant economic environment, is beginning to attract more business travel to rail (although there is still a long way to go before the potential is fully realised); [...].

It[China] had a buoyant economy outperforming forecasts. Its unemployment rate was among the lowest in years. While consolidating his power for a second term, Mr Xi proudly pointed to China's "flourishing" growth model as something other countries could emulate.