Tidal pools in the Mexican Tropical Pacific coast have received relati
vely little attention in spite of their considerable richness in speci
es and wide distribution in the region. This paper presents the first
characterization of the algal flora of this region. It analyzes the nu
mber and composition of species of the tidal pools of six localities w
ith regard to geographical distribution and its seasonal variations as
well as tidal level. 97 species are reported, 25 Chlorophyta, 23 Phae
ophyta, 34 Rhodophyta and 15 Cyanophyta. Of that total of species, 63%
were found in one locality, 23.7% in two, 11.3% in three and 1% in 4
or 5 localities. Not one species was common to all of the pools. The h
ighest number of species was found on pools of the middle and low inte
rtidal where the Chlorophyta, Rhodophyta and Phaeophyta were the most
abundant algae. Cyanophyta was more common in the supralittoral and hi
gh intertidal pools.