Still, the falls provided a singular, dramatic and daunting obstacle to navigation on this important inland waterway.

The reef proved a daunting obstacle.

There are many people who overcome daunting obstacles to achieve their dreams.

Its sheer cliffs would have proved a daunting obstacle to amphibious invasion but precision bombardment by the 17th secured the surrender of the island's defenders in less than a month.

With the growing consolidation of media worldwide, independent media makers face daunting obstacles in their efforts to introduce new perspectives into public debate.