Qantas is increasing its schedule between Adelaide and Kangaroo Island, offering double-daily flights on Mondays and Fridays.
Rex meanwhile is continuing to serve KI thanks to federal government subsidies, flying a single flight Tuesday, Thursdays and Sundays.
Qantas currently flies Monday to Saturday.
Both the South Australian Tourism Tourism Commission and the Kangaroo Island Council say flight frequency is critical for community and visitor day trips.
Double flights allow business, medical and other trips to be made on one day, negating a need to stay overnight.
SATC's manager of aviation and access, Mark Gill said Rex was due to cease flying at the end of March.
But the federal government RANS support package is being extended until September, will see Rex continue operations.
Qantas meanwhile has scheduled four Sunday evening services during the June/July School Holidays on June 27, July 4, 11, 18.
These four Sunday "one off" flights are scheduled as highlighted below, Mr Gill said.
While all these extra flights for Kangaroo Island tourism are welcome, operators that relied on international visitors remain frustrated with the lack of plan to reopen borders.
The slow roll-out of the vaccines and the lack of a tourism focus in 2020-2021 Federal Budget are industry concerns.
Craig Wickham of Exceptional KI has diversified into pop-up restaurants, laundry service and e-bikes, all serving the domestic market, which has been strong.
But closed borders were having a heavy impact on the nation's economy in the long run, Mr Wickham said, citing impacts on not only tourism, but tertiary education and agriculture.
"What frustrates me is there no apparent plan and a resignation that isolation will be okay," he said. "I worry what will be left at the end of it."
Thanks to solid vaccination programs, countries around the world, including Israel, the UK and the US, were opening back up while Australia was being left behind, he said.
Modelling by the McKell Institute suggests border closures made necessary by delays to Australia's vaccine rollout will cost the economy $16.4 billion.
Kangaroo Island, with about 50 per cent of its tourists coming from overseas prior to the pandemic, is seeing its economy suffer.
Mr Wickham said successful tourism operations in the Red Centre catering for domestic tourists had to cap numbers due to labour shortages, which was also impacting in Island businesses.
The federal government and Tourism Australia meanwhile are banking on increased domestic travel.