Long ago in Tonga there lived a chief called Sinilau. Sinilau had heard of a beautiful woman called Hina living on a far away island called Samoa and decided to go and find her. So of f he went in his canoe.
When he got to Samoa and saw Hina they fell in love and brought her back to Tonga with him.As you can image the Samoans weren't to happy about this and gave chase. So in an effort to evade them Sinilau hid Hina in a cave on the east side of Tonga and put a giant rat in charge of guarding her in case the Samoans found her, and set out himself to get warriors to stop the Samoans.
When Sinilau returned to the cave he found Hina was gone and the rat had a octopus arm in his mouth. Sinilau was angry and said to the rat “what has happened to Hina”. The rat told Sinilau that a giant octopus had come and that he had tried to fight the octopus but had lost the battle and the octopus had stolen Hina away.
Sinilau and the rat ran down to the beach, looking for Hina and as there gaze was drawn to the ocean Sinilau saw the head of the octopus and Hina's head floating away out in the distance. Sinilau cry out “ulu eua” (two heads). Ulu means heads and eua means two.
so this is how 'Eua got it's name. The cave Hina was hid in is still in Tonga on a beach called Oholie beach, they still call it the Hina cave to this day.