The following fact is mentioned in the Noble Quran:

Or like utter darkness in the deep sea: there covers it a wave above which is another wave, above which is a cloud, (layers of) utter darkness one above another; when he holds out his hand, he is almost unable to see it; and to whomsoever Allah does not give light, he has no light. (24:40)

Thanks to modern science and technology, the above statement from the Noble Quran has been verified and confirmed! We now know that at a depth of 200 meters below the ocean, the light begins to become barely visible, and the ocean begins to darken, and at 1000 meters below the ocean, it becomes completely pitch dark. Thanks to modern equipment and submarines, we humans have been able to dive down into the depths of the oceans to discover these facts, humans alone would not be able to travel more than 40 meters below the ocean without the special aid and equipment! 

Here are some good videos that allow you to see the darkness of the ocean for yourself:

http://www.youtube.com/watch?v=Q2o6t-0fU10&feature=related

http://www.youtube.com/watch?v=IZ-D6JNlnY4&feature=related

http://www.youtube.com/watch?v=a04AZ0jMjx4

All of the above videos are done by none-Muslim scientists.

So we basically have another Quranic fact confirmed by modern day science and modern day technology, we have a Quranic statement that was quite frankly IMPOSSIBLE TO VERIFY OR CONCLUDE 1400 years ago as the people did not have the means of finding out about such things, they simply had no way of knowing about the vast complete darkness of the ocean.The logical conclusion to this is that it was none other than God who had revealed this information to the Prophet Muhammed (PBUH) as it is none other than God who knows about his creation and the attributes of it.

And Allah Knows Best!