The ocean is their great filter. Ocean animals are very limited in their tool use - there's not much in the way of rocks or sticks to be had. Some shells and corals. And fire is off the table. I would expect it to be true that any technological civilization has to live on land at least part of the time.
No fire means no energy or metals which means no technology more advanced than the Stone age.
One could conceive of a species that makes its own tools the same way it makes its own shells, and uses energy from hydrothermal vents, but yeah, chemistry and metallurgy would be pretty difficult underwater.
No fire means no energy or metals which means no technology more advanced than the Stone age.