During the Pleistocene period, seas were much lower than they are today. This would have made migration from Asia to Australia much easier than it is now. However several long sea crossings would still have had to be made. These crossings would have included distances of 90100 km of open sea. It is not known what kind of boat would have been used for these crossings, but they were probably a raft made from bamboo. These first Australians were the world's first ocean travellers.