Analyses:
Creation by Nature

Interesting points: According to a link below,

-Graphics of No.1 monument (Iseki Point) circulated are scaled horizontal to vertical 2:1 in most cases, and angles are not accurately scaled.

-The entire monument is inclined 10 degree toward the ocean, which makes "pool" impossible to hold water, for example.

And the inclination was there long before the monument was supposedly formed by humans.

Online photos you can find easily by researchers on the Internet are limited in numbers and additional photos by sports divers actually help to understand what the researchers are saying.

By Researchers:

Photo gallery
(at Confronting Yonaguni) by Graham Hancock

Some of photos appeared early on the Internet next.

The Original Six Photos of Underwater Geometric Stone
Photo's by Shun Daichi -1997

Ten NEW Photos of Underwater Stone Monuments
by Shun Daichi - 1997

at Japan's Underwater Stone Monuments
Stone Monuments or Natural Geology?
by Laura Lee - 1997

By Sports divers and snorkelers:

Yonaguni Island - Underwater Ruins
by Masahiro Kaji
27 photos

EXPEDITION YONAGUNI!
by Brian D. Ehrlich
at Dive Bum Okinawa

Yonaguni-Island
by Haruo Ishii 2004 at Trip
His photos includes some photos other than the famous steps at Iseki Point, which look more natural formation.

U/W 0202 Yonaguni, Okinawa
by Aunty Helen

Mr. Kihachiro Aratake is a local dive operator who first discovered the monument (No. 1) - Iseki Point - in 1986.

Yonaguni Underwater Ruins Museum
If you read Japanese, It is Mr. Aratake's private online museum: You will find research papers, newspaper and magazine articles and so forth, all kind of information.

Dive service business web site

2004 Interview at Kurashima Story: Yonaguni)
It is in Japanese, but there are several photos in two pages.
According to the interview, he is one of many who left their home towns for Tokyo to study. He graduated from a university and continued to live in Tokyo. Fast forward, when he heard local airline decided to fly a bigger plane between Ishigaki Island and Yonaguni Island, he returned to the beautiful tiny remote westernmost island of Japan, seeing possibility to make living there with tourism. With experience as a diving instructor and professional diver, he decided to open a dive shop and started mapping diving points around the island, hanging from the bottom of a boat. That's how he came to find the monument. He says that it was a hair rising experience; he could not believe his own eyes first time he saw it, but knew it was not a dream when the scenery was still there second time he looked down.

Professor Masaaki Kimura is the leading researcher of the monuments.

Masaaki Kimura

Marine geologist, Professor, Department of Physics and Earth Sciences University of the Ryukyus, Okinawa - Ph.D. of Marine Biology. Graduated from the Tokyo University graduate school.

Interview with detailed bio. (in English)
He was the first to study the undersea ruins scientifically over a decade, as a serious "man-made monument" site with huge historical significance: It dates back at least 6,000 and possibly 10,000 years, according to him: The era when we were taught as "pre-historic". Photo Gallery below includes recent finding artifacts.

Yonaguni Monument Photos
Menu and captions are mostly in Japanese, but all the photos are by Prof. Kimura's research group at University of the Ryukyus. For example, check Kusabi-Iwa (Wedge rock)

Here is Professor Masaaki Kimura's latest position on the ruin I could find (No softening of his position as I read somewhere.):

From Abstracts of Presentation at the Annual Maritime Archaeology and History of the Pacific Symposiums ( 17th Annual Symposium, February 18-20, 2006)
**So far, I can not find full transcript of the presentation.

Artificial submarine ruins were discovered by divers during an underwater survey around the Ryukyu Islands. Also, we have discovered stone tools inside Ginama Submarine Stalactite Cave. The underwater structure off Yonaguni Island is called No. 1 monument or Iseki Point. This structure resembles ancient Okinawan castles, such as Shuri Castle and Nakagusuku Castle on Okinawa Island. These castles are called gusuku in Okinawan language. The No. 1 monument is located at a depth of about 30 meters (approximately 100 feet). The structure contains a cliff, which resembles the side of a stepped Incan pyramid. The size of No. 1 monument is approximately 200m in length, 150m in width, and 20-25m in height. Its features such as flat terraces, straight walls and surface structures of walls strongly indicate the structure to be artificial rather than natural. Additionally, we have discovered more supporting evidence such as scars driven in a wedge on the surface of No. 1 monument, a road that surrounds the structure, and a stone fence composed of huge rock fragments. This evidence suggests that the structure is man-made and it was probably built on land. The carbon-14 testing of coral attached to the structure indicated that the age of coral was around 2,000 years old. However, the uprising of the sea level by ecstatic movement of the post-Ice Age suggests the structure to be 10,000 years old.

See next for contrasting opinions.

Links are in Japanese, but thought it's worth listing, as there are almost no study published by academic scholars.

When were underwater ruins off Yonaguni created?
at Seismological Lab. of University of the Ryukyus

They say it was created about 6000 years ago by process of erosion by waves and other natural process. You can see several graphics to show process of erosion by wave.

Analysis of Yonaguni underwater ruins
at Archeology threads

Thread starting March-11-2003. Comprehensive analysis by " hammerhead". He criticizes claims made by Prof. Masaaki Kimura point by point. Well prepared even though he says he is not a scholar of any kind. Interest points; Graphics of the No. 1 monument widely circulated are scaled horizontal to vertical ratio 2 to 1, which distorts the shape greatly. The entire monument has 10 degree inclination.

LOST WORLD OF OKINAWA
Appeared in DIVER - July 1999 by Kenny Ehman

Diving for Lemuria
by JOHN ANTHONY WEST 1998

Secrets of Yonaguni
by Bucky McMahon
at Scuba Diving Magazine

Non Fiction:

Japan's Mysterious Pyramids
DVD by the History Channel $24.95

Okinawa Kaitei Iseki no Nazo (Japanese - Mysteries of Okinawa Undersea Ruins)
by Mazaaki Kimura 2000 ISBN: 4883970582

History's Mysteries: Japan's Mysterious Pyramids DVD
$24.95 at The History Channel

Fiction:
There are a few books published recently, using Yonaguni Island and monuments.

Tsubute
by R. J. Archer, March 30, 2006
SF, yes, you got it right. Yonaguni monument is used for stage for this science fiction.

Sunken Citadel off Yonaguni Island
by Dr. Masaaki Kimura

Ancient American Volume 6, Issue #39
at Ancient American
Available for purchase $8.00 (photo copy only)

Mass Media

Die Pyramide von Yonaguni
at Spiegel TV

Internet News and Broadcast

Broadcast: 5/18/2004
Reporter: Mark Simkin
FINAL STORY
SERIES 13
EPISODE 35

at OOPARTS (out of place artifacts) & ANCIENT HIGH TECHNOLOGY

Scientists Say Underwater Japanese Pyramid Definitely Manmade
19-May-2001
at Unknown Country
Ancient American Magazine editor Frank Joseph reports

Underwater Pattern - Yonagumi Japan
at Satellite Discoveries

YONAGUNI Monument
at Ancient Archeology
A SCIENTIFIC SELECTION OF WEB INFORMATION ON ANCIENT
UNDERWATER RUINS AND OTHER REMARKABLE FINDS

I do not find the author's name on the web, but sound like he or she is a trained archeologist. Most detailed analysis I can read on the Internet so far, using photos found on web sites, EXCEPT analysis by a Japanese on archeology thread above link.

Confronting Yonaguni
Chapter 27, from Graham Hancock's book " Underworld " 2002
A good overview surrounding controversy and people involved with photo gallery, up to 2001.

The Ryukyuan Submerged Landforms of the Late  Quaternary:
Possible Cultural Context and Significance
James J. Hurtak, Ph.D., Robert M. Schoch, Ph.D. (Boston  University) 2000

An Enigmatic Ancient Underwater Structure off the Coast of Yonaguni Island, Japan
by Robert M. Schoch 1999

The mysterious underwater pyramid structure at Yonaguni
by Morien Institute

Submerged stones take years off ancient "building"
by Peter Hadfield, 27 November 1999
at "New Scientist" Magazine issue 2214 Online access at $4.95

Research for submarine ruins off Yonaguni Japan
by Masaaki Kimura 2001
at Yonaguni Underwater Ruins Museum
Survey report at University of Ryukyus - in English.

It seems this is the original source for many reports on the Internet. It includes map of monument, photo of artifacts found.

Next one is one of few found by " Google Scholarly paper search". Again by Prof. Kimura.

Ancient megalithic construction beneath the sea off Ryukyu islands in Japan, submerged by post glacial sea-level change

Ancient megalithic construction beneath the sea off Ryukyu islands in Japan, submerged by post glacial sea-level change

Kimura, M.  
Dept. of Phys. & Earth Sci., Ryukyus Univ., Okinawa, Japan;

This paper appears in: OCEANS '04. MTS/IEEE TECHNO-OCEAN '04
Publication Date: 9-12 Nov. 2004
Volume: 2,  On page(s): 947- 953 Vol.2
ISBN: 0-7803-8669-8
INSPEC Accession Number: 8358747
Digital Object Identifier: 10.1109/OCEANS.2004.1405617
Posted online: 2005-03-14 08:31:25.0

Abstract
SEABAT sonic sounding, underwater robot and SCUBA diving surveys reveal the existence of artificial topographies constructed about 10,000 years ago beneath the sea off the Ryukyu islands in Japan. Features were found that look like an ancient city including stepped pyramids, roads and water canals off of the southern coast of Yonaguni Island. Its width is about 1 km/spl times/1 km and water depths vary from 0 to 35 m. Monuments are connected by roads constructed by cutting the basement rock or laying flagstones. The most elaborate one in the point is labeled as No. 1 Monument or Yonaguni Underwater Pyramid (YUP). It looks like a stepped pyramid which closely resembles a giant Gusuku from ancient Okinawa. The Gusuku is thought to be a mixed structure, part castle and part

As you have seen above, so far I have not come across studies by "academic" scholars on the Internet, except ones by Prof. Masaaki Kimura. It seems there are reasons for that:

Editorial Page
at Ancient Archeology

Concise analysis to the point with explanation why discovery of Yonaguni monument is so important.

Writing about Outrageous Hypotheses and Extraordinary Possibilities: A View from The Trenches
by Graham Hancock
at Truth is God

From a person who is "in heated kitchen" in the debate on "Man-made or natural".

Or, simply it does not pass threshold for serious study for archeology? Here's a link for comparison:

Sunken City Off India Coast -7500 B. C.?
© 2002 by Linda Moulton Howe

In Japan, things seem complicated.

According to the thread listed above, either Prof. Kimura is ignored, or circumstances are difficult for a scholar to publish opposing opinion due to politics involved all in universities, mainstream media and governmental levels. Maybe that is the reason that seemingly well-informed person is expressing his or her opinion only in obscure forum thread anonymously.

By Divers:

By Non-Divers:

Manmade structures under the Pacific- border of Mu
Feb-03-2006
at Scepchick.org
many links and photos

Yonaguni Island's Ancient Monument?
Dec 7, 2003
at Unexplained Mysteries

Yonaguni Document
at Unexplained Mysteries Discussion Forum
april 7, 2005

The Underwater Pyramid of Iseki Point?
18-02-05
at Japan Forum at Japan Reference
Many links and photos

Yonaguni: the Underwater Pyramids of Japan
Feb-2002
at Audarya Fellowship Forum

Mysterious rocks newly found in Yonaguni Island
Sept 2003 by NK ( NiraiKanai-Kitombo)

Wonder of Okinawa
by Okinawa Prefectural Government

After reading and looking photos on the Internet for a while, it's getting confusing, as there are more than one monuments (The monument you see most is "Monument No. 1") and there are findings on other islands as well. It's a good place to put information you are reading in order.

SA.WES YONAGUNI
Dive service by Kihachiro Aratake

Diving Service Marlin