Finally they released a 30-seconds trailer for the new Conan Movie in Conan-movie web site. The trailer has under-water scenes plus some text in Japanese, taken from the story published in the website:

海の底に眠る、３００年前の財宝

The treasure lying in the bottom of the sea 300 years ago

伝説の謎の挑む者たち

The people challenging the legendary mystery

シリーズは新たな進化を遂げる

The series will carry out a new development

At the end, you will hear Ran saying:

Conan-kun, where are we?

Giving you the impression she has just regained her consciousness to find herself with Conan somewhere under the water…

After Conan announces the name of the movie, he says:

“A New Conan Starts”

Edit: What Ran said can also be interpreted into "Conan-kun, where are you?", and "Conan-kun, where am I?"

The following are screen shots from the trailer: 1 2 3 4 5 6