  More than fifty years ago, Bellman asked for the best escape path within a
known forest but for an unknown starting position. This deterministic finite
path is the shortest path that leads out of a given environment from any
starting point. There are some worst case positions where the full path length
is required. Up to now such a fixed ultimate optimal escape path for a known
shape for any starting position is only known for some special convex shapes
(i.e., circles, strips of a given width, fat convex bodies, some isosceles
triangles). Therefore, we introduce a different, simple and intuitive escape
path, the so-called certificate path. This escape path depends on the starting
position s and takes the distances from s to the outer boundary of the
environment into account. Due to the additional information, the certificate
path always (for any position s) leaves the environment earlier than the
ultimate escape path, in the above convex examples. Next we assume that fewer
information is available. Neither the precise shape of the envir- onment, nor
the location of the starting point is known. For a class of environments
(convex shapes and shapes with kernel positions), we design an online strategy
that always leaves the environment. We show that the path length for leaving
the environment is always shorter than 3.318764 the length of the corresponding
certificate path. We also give a lower bound of 3.313126, which shows that for
the above class of environments the factor 3.318764 is (almost) tight.
