Once upon a time at Contact…

…which is a California convention that asks multiple sf writers to ‘game’ first contact…

we came up with a planet in which, essentially, whale-sized (and voiced) oceanic creatures more resembling giant squid make it to spacefaring tech…

Part of the notion was a religion based on pressure, the euphoria of a rise from the depths. The creatures had no vision of the stars, but they began to regard the ocean surface as a boundary they could surmount, viewed currents as a kind of topology in addition to the rock of the planet, and used subsea vents as a fire and mineral source… The first step toward flight was balloons. Then they began to think about the ultimate escape…it was worth some laughs along the way, but we thought it really pretty clever…