Wikipedia is your friend.
From
http://en.wikipedia.org/wiki/Kupua : "Mamala the surf-rider was a chieftess of kupua character. She is described as a moʻo, or gigantic lizard or crocodile, as well as a beautiful woman. She could assume whichever shape she most desired. One of the legends says that she was a shark and woman."
http://en.wikipedia.org/wiki/Kamohoalii : "In Hawaiian mythology, Ka-moho-ali'i is a shark god and a son of Haumea and Kāne Milohai. Ka-moho-ali'i swam in the area around Maui and Kahoolawe. When a ship was lost at sea, Ka-moho-ali'i shook his tail in front of the fleet and the kahuna would feed him "awa" (a name for kava, a narcotic drink), and Ka-moho-ali'i would guide the men home. He is sometimes said to have guided the ships of the original inhabitants of Hawaii from the mainland to their island home in this way."
But most of the info is at
http://en.wikipedia.org/wiki/Shark : "Sharks figure prominently in the Hawaiian mythology. There are stories of shark men who have shark jaws on their back. They could change form between shark and human at any time they desired. A common theme in the stories was that the shark men would warn beach-goers that sharks were in the waters. The beach-goers would laugh and ignore the warnings and go swimming, subsequently being eaten by the same shark man who warned them not to enter the water. Hawaiian mythology also contained many shark gods. They believed that sharks were guardians of the sea, and called them Aumakua:[42]
* Kamohoali'i - The best known and revered of the shark gods, he was the older and favoured brother of Pele,[43] and helped and journeyed with her to Hawaii. He was able to take on all human and fish forms. A summit cliff on the crater of Kilauea is considered to be one of his most sacred spots. At one point he had a he'iau (temple or shrine) dedicated to him on every piece of land that jutted into the ocean on the island of Moloka'i.
* Ka'ahupahau - This goddess was born human, with her defining characteristic being her red hair. She was later transformed into shark form and was believed to protect the people who lived on O'ahu from sharks. She was also believed to live near Pearl Harbor.
* Kaholia Kane - This was the shark god of the ali'i Kalaniopu'u and he was believed to live in a cave at Puhi, Kaua'i.
* Kane'ae - The shark goddess who transformed into a human in order to experience the joy of dancing.
* Kane'apua - Most commonly, he was the brother of Pele and Kamohoali'i. He was a trickster god who performed many heroic feats, including the calming of two legendary colliding hills that destroyed canoes trying to pass between.
* Kawelomahamahai'a - Another human, he was transformed into a shark.
* Keali'ikau 'o Ka'u - He was the cousin of Pele and son of Kua. He was called the protector of the Ka'u people. He had an affair with a human girl, who gave birth to a helpful green shark.
* Kua - This was the main shark god of the people of Ka'u, and believed to be their ancestor.
* Kuhaimoana - He was the brother of Pele and lived in the Ka'ula islet. He was said to be 30 fathoms (55 m) long and was the husband of Ka'ahupahau.
* Kauhuhu - He was a fierce king shark that lived in a cave in Kipahulu on the island of Maui. He sometimes moved to another cave on the windward side of island of Moloka'i.
* Kane-i-kokala - A kind shark god that saved shipwrecked people by taking them to shore. The people who worshipped him feared to eat, touch or cross the smoke of the kokala, his sacred fish."
How about googling (or wikipediaing) for information
before asking, next time?