The book Finite Volume Methods for
Hyperbolic Problems contains detailed descriptions of the algorithms
used in Clawpack, and many examples with associated Clawpack code.
Some of these examples are available on the
Clawpack 4.3 website but have not yet been converted.
ForestClaw,
a parallel, multi-block adaptive code based on Clawpack and
the parallel, scalable octree infrastruture in p4est.