# What is the highest velocity a spacecraft has left Earth?

The comment below @TomSpilker's answer

I'd love to see anything in LEO that can impart 20.89km/s of delta V to anything.

got me wondering what the highest velocity a spacecraft has left the Earth, relative to Earth?

This could be expressed as $$v_{\infty}$$ km/s or $$C_3$$ (km^2/s^2) relative to Earth.