The Hundred Islands are 124 islets at low tide (123 at high) scattered across
Lingayen Gulf off Alaminos, Pangasinan - a cluster of coral-limestone knobs covering
just under 17 km². Only a handful are named and developed: Governor's Island,
the highest, with its clifftop viewing deck; Quezon Island, the busiest; and
Children's, Marcos and Cathedral islands, the last two hiding the
twin-chambered Imelda Cave and a grotto beneath a triangular cleft.
The rock is fossil coral - the islands were a living reef on an ancient seabed roughly
two million years ago, in the Pleistocene, before tectonic uplift and a falling sea
left them stranded above the waterline. Ever since, the swing of the tides has gnawed a notch
around each islet at sea level, undercutting them into the famous mushroom and
umbrella silhouettes. Proclaimed on 18 January 1940, this was the very first
Philippine national park.
Dive below the surface. Orbit the camera down through the water. No open
bathymetric service covers the gulf at this resolution, so the underwater relief is modeled
from distance-to-shore: pale turquoise sand in the shallows that ring every islet, deepening
gently into the channels between them. Lingayen Gulf here is a shallow shoal - no dramatic
drop-off, just the bright green water the island-hopping boats thread all day.