The proposed algorithm, named Cliffs, is generalized to efficiently handle land inundation. The rest of the work presents testing Cliffs inundation algorithm with canonical benchmark problems: runup of a non-breaking and a breaking wave on a plane sloping beach (SYNOLAKIS 1987), runup on a conical island (BRIGGSet al. 1995), simulation of a wave-tank experiment with a scaled model of Monai Valley (LIUet al.2008), and simulation of the Okushiri Island inundation in the 1993 Hokkaido tsunami (TAKAHASHI1996). Cliffs solutions to the benchmark problems are compared to the MOST solutions obtained with the version of the MOST model benchmarked for NTHMP in 2011 (TOLKOVA2012). Given that the two models share the same propagation part, this comparative bench- marking provided a rare opportunity to observe variability in the results due to an inundation algorithm alone. Very different regimes of generation/ removal of water and momentum by Cliffs and MOST inundation algorithms, which supposedly affected the benchmarking results, have been discussed.