In the story, "Through The Tunnel" what piece of equipment does Jerry need for his adventure?

Jerry asks his mother to purchase some swimming goggles for him.

Having been humiliated by the older African boys who are able to hold their breaths for minutes as they swim through a tunnel of rock and emerge far on the other end, Jerry vows to make this "rite of passage" and prove that he, too, is no child anymore. So, when he acquires the goggles that permit him to keep his eyes open as...

Jerry asks his mother to purchase some swimming goggles for him.

Having been humiliated by the older African boys who are able to hold their breaths for minutes as they swim through a tunnel of rock and emerge far on the other end, Jerry vows to make this "rite of passage" and prove that he, too, is no child anymore. So, when he acquires the goggles that permit him to keep his eyes open as he tries to make his way through the tunnel, Jerry begins his training.

With the goggles Jerry can see; it is as though he has

...fish eyes that showed everything clear and wavering in the bright water.

Further, Jerry explores the floor of the sea and examines the great rock that the bigger boys have swum through, but he is unable to find any opening. After several attempts, Jerry finds the hole.

He knew he must find his way through that cave, or hole, or tunnel, and out the other side.

Thus, with his goggles Jerry is able to explore the rock that is hollowed out so that it can be swum through. He does this and practices until he can imitate the other boys. In this way, Jerry makes his rite of passage into maturity.