Two Illawarra grandfathers will kayak from Wollongong to Newcastle to push for greater action on climate change and a better future for their grandchildren.

Tom Hunt and Simon Leslie may be part of a movement called Rising Tide - but they were still caught off guard by the incoming water in Wollongong Harbour as they stood ashore to mark the first leg of their voyage on Saturday morning.

As their craft slipped into the water and started to drift unmanned in the middle of their speeches, Dr Leslie raced out to save it, quipping "that's the power of the rising tide" as he brought it back to shore.