In this article, scientists are investigating river channels on Earth, Mars, and Titan to see how rivers modify their landscapes. The following quote caught my eye:
Rivers are, in a way, topography bystanders that always flow downhill.
But is the above statement necessarily true? In this question the OP asks about terrestrial rivers temporarily flowing uphill on a map, but most of those answers involve "resolution" issues (where average gradient is uphill but local gradient is downhill), pressurization, or alternate physics. The answers to the linked question are all local geographic tricks. OP there is focused on earth and cartography. I'm looking for physics on alternate worlds, not necessarily talking about water. Titan has hydrocarbon rivers, Europa has cryovolcanoes, Venus has molten rivers.
Would it be possible that a certain combination of environment, chemistry and physics could create "uphill rivers" across significant distances and timescales?
For instance, a naturally occurring superfluid that flows upward between multiple reservoirs or something more exotic?
EDIT: To clarify the parameters of the question, a river is defined as a naturally occurring stream of water or other fluid flowing through a channel toward a reservoir, such as an ocean or lake. This means things like underground streams certainly classify as rivers, but something like a geyser does not (since it does not flow toward a reservoir).