I googled.

Astrobiologist lays out scenario for intelligent life on water worlds

Under the right conditions, could such water-dwelling creatures [as octopus] develop technology on an alien water world? That may be more challenging than it was for our forebears, Schulze-Makuch says.

“Fire can’t exist underwater, and fire is thought to have been essential for humans to develop technology,” Schulze-Makuch notes. However, there’s one potential avenue that he and co-author William Bains explore in their book, “The Cosmic Zoo: Complex Life on Many Worlds.”

“Perhaps smart ocean creatures could use thermal vents on an alien planet’s seafloor to supply concentrated heat energy,” Schulze-Makuch says. “Such energy wouldn’t be as portable or controllable as fire, but the underwater civilization could farm fish without fire, or perhaps use other resources to make tools and technology. As an example, long strands of kelp could be ideal for making rope.”