  Contrasting the well explored problem on how to steer a macroscopic agent
like an airplane or a moon lander to optimally reach a target, "optimal
microswimming", i.e. the quest for the optimal navigation strategy for
microswimmers, remains unsolved. Here, we systematically explore this problem
and show that the characteristic flow field of microswimmers crucially
influences the required navigation strategy to reach a target fastest. The
resulting optimal trajectories can have remarkable and non-intuitive shapes,
which qualitatively differ from those of dry active particles or motile
macroagents. Our results provide generic insights into the role of
hydrodynamics and fluctuations on optimal navigation at the microscale and
suggest that microorganisms might have survival advantages when strategically
controlling their distance to remote walls. In particular, when fluctuations
are present, choosing the optimal strategy, which appropriately respects
hydrdynamics, can halve the time to reach the target compared to cases
microswimmers head straight towards it.
