Are there deep fresh water currents within the ocean?
No, they are actual dilute salt water currents. The reason that they sink is the cold, fresh water off the continent mixes with the warm ocean water and is slightly more dense. Mix in too much fresh water and the mixed waters don’t sink. This leads to the warm water currents backing up. This is a very bad thing and will lead to the end of the world-OK, maybe not the end of the world. But it will cause the deep oceans to become anoxic, killing a large biomass. It will also shut don’t the Gulf Stream and lead to much cooler climates in Europe.
