Frozen river
A river under a sheet of ice — current still moving underneath a surface that looks like ground.
A frozen river in a dream is the dream's image of a current that has not stopped but has been covered by a surface hard enough to walk on. The ice is real; so is the water under it. The dream brings the frozen river when something in your life — a grief, a conflict, an old love — has been covered well enough that ordinary life can be conducted over the top, while the current continues beneath. A frozen river crossed by a marked safe route is the dream affirming the cover and the careful use of it. A frozen river with someone gone through the ice mid-crossing is the dream noting that the cover was thinner than it looked, and the current beneath is no warmer for having been hidden.