Besides the metal net, on the road of the left side of the school.
Apparently there's only one toad living on the Hawaiian islands: the cane toad! This thing is sitting in sea water. Hence the name?
Length 7-8 cm
Caught in stream bed (gravel)
Same animal as photos from jameyred, http://www.inaturalist.org/observations/3248013
There are additional photos of this same animal. I have some more that are not as well-lit or focused, but might have other distinguishing characteristics visible.