Guy in the dive shop steered me away from a different set of fins because he
said they are fine for snorkeling but won't provide the scuba diver with
enough pull to move body and gear through the water in any current. Hence, I
think we're talking about the ability to move an equipment load in addition
to the person - not an issue when snorkelling.

This is all new to me - the only fins I've ever used are the open heel
scubapro blade fins I got at the start of my OW training. I've used those
for tropical diving but figured I'd go with something that will fit in the
carry-on.

Thanks.

Most people that refer to a snorkeling fin presume it's for someone that
will put along on the surface.  They normally mean that it's OK for poking
along, but not powerful enough to push a diver, in full gear, against a
noticable current.

Freediving fins are a whole different animal and, at a guess, probably
aren't good for snorkeling.  My Mares Quatro Power fins are what Mares
advertises as a freediving fin.  Most freediving fins are long, narrow and
flexible at the tips.  Mine are longer and wider than most fins, but not
nearly as long as other freediving fins.  They're good fins for diving when
acceleration or power are needed, like when I'm hunting or when diving in
stiff currents.

They are not, however, worth a sh.t for snorkeling, i. e. on the surface.  I
don't know if it's the length, or the amount of water they move with each
stroke, but it's near impossible to keep them below the surface.  They
break, or suck the surface down, on almost every stroke.  The only way I've
found to keep them in the water, where they do me some good, is to turn so
that my kick is horizontal instead of vertical or to foll over on my back, a
position that forced the fins deeper.

My Mares TRE fins and Jayna's Mares Avanti fins are a good compromise.
They're a good snorkeling fin with enough power for any but the most
vigorous diving.  They're also the ones, of what I own, that I'd chose for
wreck or cave penetration.  In truth, even they move too much water to be
ideal where silt may become a problem.  For that, you need something that
moves almost no water at all, like Jet Fins 8^)).  They don't, however, move
nearly as much water as the Quatro Power fins.

BTW, all of the fins I mentioned are full foot fins.  I leave the less
efficient open heel/strap fins to those who need thermal protection during
their dives and to those that, for good reason, prefer not to move as much
water as easily.

Lee