What helps Mafatu to regain his energy in Call It Courage?

When Mafatu’s canoe crashes into the coral reef in chapter 2 of Call It Courage, Mafatu is severely dehydrated and malnourished due to days spent on the ocean. He also sustains an injury on his right leg from banging it against the coral, yet he somehow still manages to swim to a nearby island, where he collapses on a mossy bank.
In Chapter 3, Mafatu must find several items to regain his energy. Thankfully, he literally stumbles into the most vital of these things—water—when he finds a fresh pool near the bank. He drinks deeply, and

Its cool magic stole through his tissues, bringing with it new life and restoring force. He sighed . . . relishing the strength that quickened his tired body.

After resting, Mafatu feels stronger, but must still treat his injured leg with lime juice and purau leaves, which he finds on a nearby tree.
Once his wound is tended, Mafatu discovers and follows a trail lined with several trees full of coconuts, breadfruit, wild bananas, oranges, guavas, and mangoes. He also catches sight of a wild boar and imagines killing and eating it, but opts instead to satisfy his hunger by picking the readily available fruit of a mango tree and eating his fill.