The exploration and settlement of the Pacific Ocean is one of the great migration stories of humankind, even if some of the dates are open to discussion.   Originating in Taiwan and adjacent mainland China, the proto-Polynesians made their way down into Near Oceania reaching the Bismarck Archipelago by about 4000 BC.  About this time outrigger canoes started to be used. 

An eastward push after about 1500BC saw them they reach the Marquesas by about 0 AD.  Subsequent explorations took them north to Hawai’i, south-east to Rapanui (Easter Island) and south-west to Aotearoa-New Zealand.  Some accounts cite the path of the annual migration of the Koekoea (Long tailed cuckoo) as one of the guides that assisted Maori to find Aotearoa.   

While exploration could be undertaken on quite modest-sized canoes, settlement of new islands required larger vessels.  Double-hull canoes which can have substantial platforms between the hulls were widespread across the central Pacific Ocean at the time of the first visits by Europeans.  The largest portion contained canoes with equal or subequal hulls.  The extent of unequal hulls, like the Fijian ndrua, was restricted to the Fijian Islands, although they later spread to include Tonga, Samoa and Tuvalu.

A starting point for further reading could include:

Migration: Te Ara - The Encyclopedia of New Zealand

Pacific Canoes: Haddon AC and J Hornell, (1936-38), Canoes of Oceania, Special Publication 27-29, Bishop Museum Press, Honolulu