  Here we characterize the motility of athermal swimming droplets within the
framework of active rotational diffusion. Just like active colloids, their
trajectories can be modeled with a constant velocity $V$ and a slow angular
diffusion, but the random changes in direction are not thermally driven.
Instead, $V$ is determined by the interfacial tension gradient along the
droplet surface, while local micellar fluctuations lead to droplet
reorientation with a persistence time $\tau$. We show that the origin of
locomotion is the difference in the critical micellar concentration $\Delta$CMC
in the front and the back of the droplet. Tuning this parameter by salt
controls $V$ from $3-15$ diameters $d/s$. Surfactant concentration has little
effect on speed, but leads to a dramatic decrease in $\tau$ over four orders of
magnitude. The corresponding range of the effective diffusion constant $D_e$
extends beyond the realm of synthetic or living swimmers, in which $V$ is
limited by fuel consumption and $\tau$ is set by temperature or biological
activity, respectively. Our tunable swimmers are ideal candidates for the study
of the departure from equilibrium to high levels of activity, on both the
single particle level and their collective behavior, including the
motility-induced phase separation (MIPS).
