How would aquatic aliens create technology? ( Think late 90's style, and by that, I mean: Phones, metallurgy, electricity, public transportation (think trains), books (and ink that would not just dissolve in water), oven and stoves, (maybe even a tv like thing?), even the building themselves). Suppose that they have no access to land whats so ever, and that the water that they live in is not really water, but a liquid that can with no problem at all, have sufficient amount of oxygen to sustain hot-blooded mammalian creatures through reasonable sized gills, and the planet is mainly made of shallow (around under 150 meters deep) oceans, and very little of it is a desert.
Your aquatic species could develop any level of technology we Telurians (People of Earth) have developed using the same processes we've developed but they might have different motivations.
Assuming they have a way to manipulate the things in their undersea world, they have to have culture, which gives rise to language, which gives rise to what we consider thought. Thought gives rise to questions, which engender answers and disagreements. All this, obviously, leads to war.
War means better weapons and defenses than the other clams or guys. This means they learn how to construct defensible enclosures out of seaweed, hermit crabs and coral reefs. Which means they figured out how to make tools out of things that can cut seaweed, hermit crabs and so on.
Once they've learned to fight and survive and have time to start questioning why coral is like coral, they can begin to explore the concepts we know as chemistry, physics, and mathematics. Once intelligence and sapient creatures start on that path, there is no turning back since more and more of the world starts making sense, at least until some nabob invents economics and messes everything up for a while. But, that is a different discussion.
Once minds start trying to figure out the world around them using science, they then can figure out to make things they need or want to make their lives longer, safer, healthier, etc. Given their world, they may find ways to create biological solutions were we Telurians depend on physics-based solutions. But, once they have a need, they can find a solution whether how to make electricity or how to melt and purify silicon.
The long and the short of it, pretty soon you have Facebook and StackExchange and sneakers.
Albeit, it's very different from what we would know since they have a very different world than we do, and have different motivations as a result of their environment.
Human technology began with fire. Once we learned to make fire, we learned how to melt and shape metal. Chemistry, too, stems mainly from fire; heating and burning things to figure out what they were made of.
An aquatic species is going to have a hard time going this route, but they have an advantage that land-dwellers lack - the richness of undersea life. Aquatic organisms are far less restricted morphologically than terrestrial ones, and many of them have exotic chemistry and hard shells, both of which could prove potentially useful to a budding sapient species.
Instead of forging metal weapons, an aquatic species may grow them by domesticating creatures like snails and clams, and breeding them to produce shells in the shapes that are needed, ranging from sharp speartips and knives to shovels, bowls, and armor.
There is a species of sea snail that actually incorporates iron into its shell (it lives near deep-sea vents and eats iron sulfide, chemically separating the iron and using it for protection). If a similar species could be domesticated and bred, this could produce more advanced tools.
As the species grows more advanced, it could begin exploring the various different poisons and other chemicals produced by species in its environment, and by studying how they interact it could develop theories of chemistry without the use of fire.
This could lead to a more advanced understanding of physics and ultimately produce technology not unlike our own, although it is likely that they would be far more inclined to use biotech rather than metallurgy, since they'd be building off of thousands of years of experience working with living things.