  We identify the presence of a continuum percolation transition in model
suspensions of pusher-type microswimmers. The clusters dynamically aggregate
and disaggregate resulting from a competition of attractive and repulsive
hydrodynamic and steric interactions. As the microswimmers' filling fraction
increases, the cluster size distribution approaches a scale-free form and there
emerge large clusters spanning the entire system. We characterize this
microswimmer percolation transition via the critical exponents associated to
cluster size distribution $\tau$, correlation length $\nu$, mean cluster size
$\gamma$, and clusters' fractal dimension $d_f$. We are able to show that two
scaling relations, known from percolation theory, also hold for our
microswimmers. A real-space renormalization group transformation can
approximately predict the value of the exponent $\nu$. This finding opens new
vistas on microswimmers' congregative processes.
