After receiving feedback on my worldbuilding project, I realized I needed to go back and get the basics down. What Europa and its oceans look like. I built up an expansive ecosystem, but while the animals have been established, the setting not so much. And I wanted to fix that.
Europa
Europa is the smallest of Jupiter’s moons, also being slightly smaller and less massive than Earth’s Moon. It’s around 670 000 km away from us.
The Surface
Europa’s surface is covered in a think shell of ice, ranging from a few kilometres to as much as 30 km thick. It’s covered in fractures, that ice criss-cross along its surface and allow a few stray rays of sunshine to peak through. It’s very smooth compared to other solid objects in our solar system as it lacks any kind of large-scale geological features like mountains and craters. The surface is a pale grey, with yellowish-reddish-brown regions from sulphur deposits.
The Ocean
Water makes up about 6% of Europa’s total mass. In comparison, Earth is only about 0.02% water. This means the oceans on Europa are much vaster and deeper than on Earth – about 100 km of depth.
The Shallows
On Europa, what we understand as the Shallows is not the same of what we understand on Earth. Given Europa’s distance from the sun and its layers of ice, there is no life directly beneath the surface of the water. It’s too cold. Here, the Shallows are at about 85km – 70km depth. Life here is sparse, mostly, only existing around undersea mountains that spew luke-warm water coming all the way down from the depths.
The Mid-Levels
The Mid-Levels start around 95km-85 km. It’s a near black vastness, stretching out forever. Here is where many of Europa’s large predators hunt given it’s both just warm enough for them to thrive, but also less obscured by geological formations than the deeper levels. This allows them to travel efficiently as they often cross great distances in search of food.
The Abyss
At 100km – 95km the Abyss starts. This region is marked by mountains and cliffs that have formed over millions of years. The hot water rising from the bottom cools down as it drifts upwards, but here is where the sweet spot lies. It’s warm, very comfortably so, and many creatures big and small have settled here, forming a vast and rich ecosystem in total darkness.
The Bottom
The Bottom of Europa is covered in hydrothermal vents; they spew hot water loaded with dissolved gases and minerals, which quickly cools down and forms solid structures around the vent – these are also known as vent chimneys. Depending on the temperature these vents expel white or black “smoke”.
White smokers occur at lower temperatures, they appear white because of the minerals they carry. These are usually silica and barite. Black smokers are hotter and carry iron sulphides for the most part.
Here is where life on Europa first began and continues to thrive.
Sources
Wikipedia. Die freie Enzyklopädie (07.06.2026), s.v. Europa (moon) https://en.wikipedia.org/wiki/Europa_(moon) (zuletzt aufgerufen am 20.06.2025)
