Mafumu waded into the river. It was not running very swiftly just there, for it was almost on the level. It was deep, however, and the boy had to swim. He began to make his way up the tunnel to see how far he could go with his head above the water. His head knocked against the roof as he swam — and presently he found that the water touched the roof! So he had to swim under the water, and hoped that before he choked the roof would rise a little and give him air to breathe!
Mafumu was a good swimmer, and was able to hold his breath well — but his lungs were almost bursting by the time that he was able to find a place to stick up his head above the water and breathe again. Even so, the roof fell low again almost at once, and the water bobbed against it. How far would it be before it rose again and Mafumu could breathe?
He had to try. There was nothing else to do, unless he and Jack were to go right back. So he took an enormous breath, dived down and swam vigorously below the water, trying the roof with his hand every now and again to see if he could come above the water and breathe.
He was rewarded. The roof suddenly rose up and the tunnel became a large cave! Mafumu waded out of the water gasping and panting, delighted that he had not given up too soon!
He sat down for a few minutes to get all the breath he could. He had to go back and bring Jack through now! He did not know if the other boy could swim under water as well as he, Mafumu, could!
Back went Mafumu, knowing exactly where to rise and breathe, and where to dive under and swim back to where Jack was anxiously awaiting him, wondering what in the wide world had happened!
Mafumu tried to explain to Jack what he was to do. Jack understood only too well!
“Lead on, Mafumu,” said the boy, taking a deep breath. “I’m a good swimmer — but I don’t know if I’m as good as you are! Go on!”
So into the river went both boys, swimming below the water where it touched the roof, and coming up, almost bursting, in the place where the roof lifted a little so that they might breathe.
Then into the water they went again, shivering, for it was icy-cold, and once more swam as fast as they could up the low tunnel, their heads bumping the roof till they came thankfully to where the tunnel opened out into the large cave! They crawled out of the water, panting, and sat down to get their breath. Their hearts beat like great pumps, and it was some time before both boys could go on.