Mr Arrowsmith said he was seeking a new challenge and was giving himself plenty of time for new opportunities to open up, but was interested in the export sector.
"I just wanted to give plenty of notice to make sure my move was pushing a very positive message for the industry and the organisation, which is in a very healthy state," he said.
"It's time for somebody else to take over the reins and take it to the next step."
Mr Arrowsmith said he was confident his team would keep working towards the goal of making tourism in the Bay grow into a $1 billion industry by 2030.
"During the past four years, I've seen this region through some very interesting economic and environmental times.
"Together with my board and team, I've had the pleasure to lead an important economic sector to new heights, adding over $30 million to the local gross domestic product each year of service, bringing the annual tourism spend from $655 million to $773 million per annum.
"This means our region is the sixth largest tourism region in New Zealand. Comparatively this now brings the region's tourism spend $180 million ahead of Rotorua, $320 million ahead of Taupo and $80 million ahead of Hawke's Bay.
"This excludes cruise spend, estimated to be an additional $40-$45 million spend value to the region. Cruise ship visits, size and frequency have also increased with another 30 per cent growth booked in for the next two seasons, bringing our annual visits from 79 to 100 to 112 respectively."