"I had so many ideas and concepts that I just can't replace. It's a loss, it sucks, it's a drag but s*** happens."
The 42-year-old creates activist art, raising awareness for environmental issues.
He is part of a group of international artists who are taking part in the Murals For Oceans Festival, a global street-art project.
His was one of 30 murals that have been painted around Napier at a value of around $500,000.
None of the artists are paid however and the festival survives on a budget of a little over $60,000.
Similar events have been held in Mexico, Vietnam, Sri Lanka, Japan and across the United States to highlight the plight of the world's oceans.
Fourteen of the murals are being created around Ahuriri, four are going up along West Quay, two are at the Napier Port while the rest are in the CBD, including four walls of buildings owned by the Napier City Council.
Mr Botkin endured early starts, late finishes and five days days of painting all for free.
His mural features a New Zealand long finned eel intertwined with a giant octopus sporting a moko.
He said despite the incident he will take home fond memories of Napier.
"It is such a boutique quaint city with a very Victorian feel. The people have made us feel so welcome so this certainly doesn't sour my time here. There is just too much to celebrate."
Napier councillor Maxine Boag said for Mr Botkin to have been robbed of his backpack is appalling and shameful.
"To have him lose gifts for his children, his phone and stereo, and worst of all his sketch pad, is very sad. I'm hoping the community will reach out and tell Jason they appreciate his work, and the huge personal effort he has made for us."
Ms Boag said the council and community response has been hugely supportive digging deep to provide accommodation, transport, paint, walls, lifts, food, scaffolding and showing their appreciation for a job which would have cost 50,000 to 60,000 had they been commissioned.
She said if anyone wanted to send him support, he will be staying at the Six Sisters in Napier for the next two days.