  For a set of robots (or agents) moving in a graph, two properties are highly
desirable: confidentiality (i.e., a message between two agents must not pass
through any intermediate agent) and efficiency (i.e., messages are delivered
through shortest paths). These properties can be obtained if the
\textsc{Geodesic Mutual Visibility} (GMV, for short) problem is solved:
oblivious robots move along the edges of the graph, without collisions, to
occupy some vertices that guarantee they become pairwise geodesic mutually
visible. This means there is a shortest path (i.e., a ``geodesic'') between
each pair of robots along which no other robots reside. In this work, we
optimally solve GMV on finite hexagonal grids $G_k$. This, in turn, requires
first solving a graph combinatorial problem, i.e. determining the maximum
number of mutually visible vertices in $G_k$.
