Preston Dennett is one of many researchers that has looked into the mysterious things that fly under the water & in the sky. Out of this world & even beyond this galaxy and other realms throughout the cosmos. www.fatemag.com/category/subjects/ufos
Waterufo.net is a very appropriate site on this topic. Its not just large high speed crafts, but giant unknown sea creatures that could be making some occasional sounds.
www.ghosttheory.com/2012/02/28/strange-recordings-from-the-deep, http://pijamasurf.com/2012/05/camara-robotica-capta-indescifrable-criatura-submarina-video
The big underwater sounds seem to travel a fair distance as do some of the ones from underground.
Hiding various things underwater would make sense. www.mysteryportals.com/Underwater_UFO_Base_in_S__California.html
Not just in oceans but large lakes provide ideal hiding spots.
http://theparanormalpastor.blogspot.ca/2011/09/does-lake-erie-harbor-underwater-ufo.html
Several high speed underwater shapes have been detected with sonar through the years.
http://articles.nydailynews.com/2012-01-29/news/30676997_1_mysterious-object-sonar-expert-side-scan-sonar
The Baltic_Sea is a cold water area with its own secrets.
http://rt.com/news/prime-time/baltic-sea-ufo-exploration/
Of course, for many unless there is actual proof of a submerged craft, it may as well be just another rock formation.
www.popularmechanics.com/technology/aviation/ufo/underwater-ufo-get-real-experts-say,
http://c-shapes.blogspot.ca/2012/06/jv.html
This is an interesting story, but its in need of a lot of proof.
http://weeklyworldnews.com/aliens/10405/titanic-sunk-by-underwater-ufo/
Preston mentioned The Shag_Harbour_UFO_incident. Something very peculiar did happen in those waters.
www.ufocasebook.com/Shagharbor.html, www.ufodigest.ca/article/shag-harbour-ufo-incident,
http://ufos.about.com/od/bestufocrashcases/p/shagharbor.htm, www.ghosttheory.com/2012/02/26/the-1967-shag-harbour-ufo-incident
The 1998 movie, Sphere depicts a spaceship from the future that has sank to the bottom of the ocean.
www.ghosttheory.com/2012/05/02/alien-visitors-are-they-us
Kenn-Thomas looked into the Maury_Island incident.
www.ufoevidence.org/documents/doc1041.htm, http://kevinrandle.blogspot.ca/2010/07/maury-island-ufo-crash.html, www.unexplained-mysteries.com/viewnews.php?id=185854, www.ufocasebook.com/mauryisland1947.html
It could just be another hoax or a serious cover up.
Unless this is a publicity stunt this looks like a couple of the MIB.
www.unexplained-mysteries.com/viewnews.php?id=226039, http://silverscreensaucers.blogspot.ca/2012/05/new-men-in-black-3-clips.html
