Complex sentence: Having no radio, the crew were unaware of the declaration of war and finding all of the buoys and other navigational markers missing, they attempted to pick their own way in through the Narrows, the channel that threads through the barrier reef.
Split into simpler sentences: Having no radio, the crew were unaware of the declaration of war. Finding all of the buoys and other navigational markers missing, they attempted to pick their own way in through the Narrows, the channel that threads through the barrier reef.