We present the first direct measurement of vertical motion in the deepest a
tmospheric layers of a penumbra, obtained at hitherto unreached spatial res
olution. Isolated hot upflows in the inner penumbra feed the horizontal Eve
rshed flow that is observed in the mid and outer penumbra. We discover cool
downflows which surround the hot upflows in the inner penumbra. At the out
er edge of the penumbra, the Evershed flow terminates in a ring of downflow
channels. The upflows transport a sufficient amount of energy to account f
or the observed brightness of the penumbra. These measurements have therefo
re significant implications for understanding the mass balance and the ener
gy transport in a sunspot penumbra.