I have a vague memory of an odd children's book/story I read when I
was between 6-10 years old, would have been in the mid-to-late 1970's.
 I live in Canada, so it likely would have been either a Canadian or
American author.  I'm pretty sure it was an illustrated children's
book (as opposed to a novel), probably not too long.

The protagonist was a child/man who had the remarkable ability of
holding vast quantities of water in his mouth.  The story goes through
a progression of events of his taking in escalating water volumes; it
culminates in an incident where he sucks up all the water in the
sea/ocean and his greedy friend runs off to gather previously sunken
treasures on the seabed.  The friend does not return in time, and the
protagonist cannot hold the water any longer, ultimately expelling it,
and, if I recall correctly, causing his friend to drown.

I know it sounds pretty strange, but I have quite a vivid memory of
this story and I wasn't doing any hallucinatory drugs at that age, so
I'm pretty sure it actually existed.

I believe you are remembering a children's book called "The Five
Chinese Brothers," by Claire Huchet Bishop. I loved this book when I
was a kid! One of the titular brothers has the ability to suck the
entire ocean into his mouth.

"Originally published in 1938, it centers around five brothers who
each have a unique quality. The First Chinese Brother has the ability
to swallow the sea. The Second Chinese Brother has an iron neck. The
Third Chinese Brother can stretch and stretch and stretch his legs.
The Fourth Chinese Brother can not be burned. And the Fifth Chinese
Brother can hold his breath indefinitely."

Amazon: The Five Chinese Brothers
http://www.amazon.com/Chinese-Brothers-Claire-Huchet-Bishop/dp/0399233199

"The Five Chinese Brothers... is the story of five outwardly identical
sons, each of whom has one uniqueness. It begins with brother number
one whose gift is that he can suck up the entire sea and hold it in
his mouth. While he's doing that, he can walk about the seabed
scavenging fish from the ocean floor. Of course, he can't hold the sea
in his mouth forever. One day, against his own better judgment, he
lets a boy go with him to the beach. He sucks up the sea and the boy
walks out; when the boy refuses to return to high ground the brother
must finally spit out the waters, and the boy is drowned."

God's Friends: A Eulogy For My Father
http://godsfriends.org/Vol7/No3/Venable.html

"Each brother has a special ability. The first brother is able to hold
all the water of the sea in his mouth. One day he sucks up the sea so
he can pick up fish off the bottom. A boy comes out into the empty sea
and starts making faces at the first brother, who can't hold the sea
for long and tries to warn the boy before he lets it spill out. But
the boy gets caught up in the water and drowns."

Everything2: The Five Chinese Brothers
http://everything2.com/index.pl?node_id=613467

My Google search strategy:

Google Web Search: "five chinese brothers" ocean OR sea
://www.google.com/search?hl=en&q=%22five+chinese+brothers%22+ocean+OR+sea

I hope this is the right book. If it is not, please request
clarification; I'll be glad to offer further assistance before you
rate my answer.

Best regards,
pinkfreud

BINGO....that's it!  Thanks for the excellent and fast reponse, pink;
can't wait to get my hands on the book again.

Thank you for the five stars and the nice tip!

~Pink

It's so tempting to try to find a book that Pinky hasn't read.  :-)

" The first brother is able to hold  all the water of the sea in his mouth."
This was a chinese folk tale to warn children of the dangers that
would precede a Tsunami.

Kemlo

>> It's so tempting to try to find a book that Pinky hasn't read.

I read very few westerns, and not many chick-lit romances, so I bet
you could find a whole lotta books in those genres that I've never
even heard of. :-D

HI Pink,
If you haven't read those, I certainly haven't, but I'm thinking 
(well, that's what I call it ;-) ....

Myo