There is considerable archaeological discussion as to the route taken by the first colonisers. People appear to have arrived by sea during a period of glaciation, when New Guinea and Tasmania were joined to the continent; however, the journey still required sea travel, making them among the world's earliest mariners. Scott Cane wrote in 2013 that the first wave may have been prompted by the eruption of Lake Toba. If they arrived around 70,000 years ago, they could have crossed the water from Timor, when the sea level was low, but if they came later, around 50,000 years ago, a more likely route would have been through the Moluccas to New Guinea. Given that the likely landfall regions have been under around 50 metres of water for the last 15,000 years, it is unlikely that the timing will ever be established with certainty.