Comprehension: Read the following passage carefully and answer the question:…

Comprehension:
Read the following passage carefully and answer the question:

At low tide he walked over the sands to the headland and round the corner to the little bay facing the open sea. It was inaccessible by boat, because seams of rock jutted out and currents swirled there treacherously. But you could walk there if you chose one of the lowest ebb tides that receded a very long way. You could not linger on the expedition, for once the tide was on the turn, it came in rapidly. For this reason very few people cared to explore the little bay and the cave at the back of it.

But the unknown always drew this man like a magnet. He found the bay fresh and unlettered, as it was completely covered by the sea at high tide. The cave looked mysteriously dark, cool and inviting and he penetrated to the farthest corner where he discovered a wide crack, rather like a chimney. He peered up and thought he could see a patch of daylight.

Q. When the man passed through the cave, he discovered ______.