[Sharlin]

I live next to Suolijärvi, "bowel lake". I guess the name reflects its shape: https://maps.app.goo.gl/w6wUmBF6m5r6U3eJ9

There's also Särkijärvi, "roach lake" (as in the fish) nearby; presumably there is (or once was) a healthy roach population there.

The most common lake name in Finland is Pyhäjärvi, literally "holy lake" or "sacred lake", but apparently the original meaning of the word pyhä was something like "demarcated" or "dedicated" (in modern Finnish the verb pyhittää means "to sanctify" but also "to devote" or "to dedicate"). So many of these waterbodies may have been named after ancient border or boundary agreements of some sort, pertaining to fishing or hunting rights for example. Rather mundane stuff despite the word's contemporary meaning!

[marcosdumay]

I live close to the Paranoá lake, that on the indigenous language it comes from means "lake"...

I'd say it's descriptive.

[Sharlin]

I also found Vesijärvi on the map in the next municipality over. "Water lake". As opposed to what other type of lake exactly?

[masklinn]

Salt? I don't know if there are any in finland tho.

Does finnish differentiate between fresh and sea water? If it's near the coast I imagine it could have been named thus to differentiate it from a nearby gulf?

[Sharlin]

"Vesi" means generically any kind of water and there are compound words for seawater and freshwater just like in English. There are several Vesijärvis in Finland, and now that I googled it, it's conjectured that the word vesi in the name does not refer to the water in the lake but rather derives from an archaic word meaning "outlet river".