I saw a recent ruckus in another thread (the "Roy Tassell Memorial" Flying Boat Quiz) about what constitutes a "seaplane" versus a "flying boat" etc. and I wanted to comment further. Especially since I kinda found it hard to believe there was any contention over that issue.
For the record, any aircraft capable of repeated operations off of, from, or in and out of the water is a "seaplane"
(even if it is really only capable of flying off of almost ripple-less lakes, rivers, or other protected "fresh water" waterways.)
"Flying boats" and "float planes" are both valid subsets of the larger entire set of "seaplanes" in general (they are all "seaplanes")
but those two basic subsets are each subdivided as well on the basis of whether the specific aircraft in question is also an "amphibian" or not.
There are amphibian flying boats that are fully equipped to "land" on either water or terra firma at the pilot's discretion - and not (i.e. "pure" flying boats that must "land" only in the water and which can be "beached" only after some kind of detachable or temporary "landing gear" is installed) and there are also both amphibious float planes and not - i.e. "straight" float planes - but ALL are "seaplanes".
Is that clear enough?