What is an analogy for active transport and passive transport

The movement of molecules through membranes based only on concentrations is passive, requiring no energy expendature such as water moving through a membrane as in osmosis.

Active transport requires an energy expenditure and selectively moves substances against a concentration gradient. For instance sodium is transported into many cells by carriers in the cell membrane and requires ATP as an energy source.

Active transport analogy: Swimming against the current (water current)

Passive diffusion analogy: Swimming with the current (water current)