Nudibranches  - are molluscs - close relatives of land slugs - but in fun contemporary colours ! They are distinguished by usually having feathery gills in the middle of their backs and two sensory devices (rhinophores) on the head end. They are unusual amoung moluscs in that hey have no shell.

Anne and I made these our special interest during the cruise, we kept our eyes open for them and saw a few most dives, but the majority of these pictures were taken during one great dive at Puerto Galera on Sinandigan wall.  Anne says she saw another 50 beyond what I filmed, there was such a profusion of species to see and good conditions for using the video.  The dive was at 20m to 6m in no current. More Extensive Nudibranch page
A Chromodoris , but I can't find this colour pattern in the books, so don't know a species for it
Three chromodoris bullocki , with the nearer two mating, being hermaphodites each is male and female and they exchange genetic material through tubes from their right sides.  These were at crocodile island near Borocay.
A Glossodoris nudibranch-  very frilly.  Most nudobranchs eat particular sponges or ascidians that are characteristic of their species, can't see if this one is easting anything identifying.
These are the eggs of Nudibranchs, not sure which type as they don't stay around to look after them. 
Pauline spotted this one first, one of three on the sand on the bottom of Sabang Bay in just 8m of water.  The book says it is a Chelidonura varians,  The broad flap above the head is thought to help them burow in sand.  We saw it on the dive when the camera did not work so I had to go back an hour later but all the subjects had waited for me !
This is of Nembrotha genus without doubt but what species ? - no idea.   Nembrotha nudibranchs cannot fully retract the gill structure, it always waves around like a tree
Another Nembrotha at Sinandigan, maybe N.kubaryana

There is another group of Nudibranchs with long tassles all along their bodies, we saw a few but never got a good picture - a reason to go back for more <G>

A Phyllidia genus, these ones have the gills hidden along the sides under the edges so not visible.
 <----  Probably Phyllidia varicosa

Can't tell you much about these two below, not even sure where I saw them.

But I know this Chromodoris Kunei was just off Borocay