Most ships lost at sea were the victims of huge waves caused by hurricanes or large storms. But it was a lack of waves that contributed to the Titanic hitting the iceberg at 11:40 pm on April 14, 1912, and sinking on the 15th, a hundred years ago. On that night the weather and the sea conditions were perfect -- but for the Titanic, they were too perfect.
There was no wind, and thus there were no waves. It was a flat calm. It was also a dark moonless night, which made it difficult to see an iceberg in the distance. On such a night, waves would have made the iceberg more visible. Even small waves would have caused a bright phosphorescent line around the base of the iceberg, due to the millions of dinoflagellates that migrate to the ocean surface at night.
These tiny plankton glow brightly even with the slightest disturbance. (Sailors had seen this phosphorescence many times as they rowed through such waters, every stroke causing a glow that clearly outlined each oar.) On that night there was not even a gentle swell that could have caused a phosphorescent line around the iceberg.
These were extremely rare conditions for the North Atlantic in April. On almost any other night the huge iceberg would probably have been seen by the lookouts in enough time for the Titanic to avoid hitting it. For more Ocean facts check out Dr. Bruce Parker's book: The Power of the Sea.