Minister's bike ride highlights routes.
After setting off yesterday, he is scheduled to cycle back into Cardiff Bay at about 5pm on Wednesday.
The minister is promoting cycling as a form of sustainable travel and recreation, and an enjoyable way of maintaining health and well being.
He will also be visiting some key attractions and people along the way.
"I am very much looking forward to cycling through Wales' stunning countryside and to making use of some of our fabulous cycling routes which attract so many tourists to Wales," he said.
"Although 285 miles might be a bit much for some people, I would encourage anyone to get out on their bikes.
"It really is a great way of keeping fit, and an enjoyable way of enjoying Wales' unique coast and countryside, particularly over the Easter break.
"Cycling is also often a quick, cheap and easy way of travelling short journeys and could really help us to reduce our reliance on cars and cut down on our carbon emissions."
As part of his bike ride the minister will stop off in Merthyr Tydfil, where he will join a local youth group in clearing litter from a section of the Taf Trail.
Mr Griffiths will also be joined by a representative of Sustrans, the charity that supports sustainable travel, and by Welsh Government staff for short legs of the journey.
He will be tweeting along the way - follow him @EnviroMinWales Proceeds from the bike ride will be passed to official Welsh Government charities for 2012 including the Alzheimer's Society and Tools for Self Reliance Cymru.