- Learn Muay Thai boxing
- Have cookery classes
- Have scuba lessons
- Go to the Full, Half, Black Moon Parties, or go to any of the big parties
- Sleep with a bargirl in Baan Tai
- Do an island boat tour
- Organise a fishing trip
- Extend your visa by pretending to study Thai
- Take up kiteboarding
- Rent a motorbike and chance riding the roads around Koh Phangan
- Go snorkelling at Koh Ma
While being dangerous and reckless, it shows the Latvian has balls. From the picture I'd say he was in his 50s. He is currently living on the deserted beach of Haad Khontee, next to Haad Rin. He forages for fresh water and fishes for sustenance. Apparently he makes the odd visit to Haad Rin to stock up on coffee and other essentials. Is he off his rocker? Maybe. Is he over-staying his visa? Maybe. Is he doing the usual stuff in Koh Phangan? No.
A few years ago Greg Spurgin started in Koh Samui and kayaked to Koh Phangan and other places in the Gulf of Thailand. He was clearly an expert kayaker. He circumnavigated Koh Phangan staying in obscure inlets and islands and avoided paying accommodation and the company of others. He stayed one night on the tiny island of Koh Kong near Thong Nai Pan. He made a blog about his journeys on his kayak. It is one of the best records of a holiday to Koh Phangan I have read. He has visited places I suspect very few other Westerners have on and around Koh Phangan. Here is his blog - http://www.gregspurgin.com/thailand/thailandkayak2.htm
You read various things about the treks to be done in Koh Phangan, but you meet few people who have actually done them. It appears the easy option of a taxi or the exciting option of motorbike rental seems to be the winning options for most people.
And then there is the interior of the island. The island is 90% virgin forest. It holds a wealth of flora and fauna (supposedly including deers) that nobody gets to see who are doing the typical beach and party holiday. Thong Nai Pan Magazine blog has some information about snakes, birds and other animals that inhabit the forest.
The closest to eco-tourism on Koh Phangan is Jungle Flight. It is run by a local farmer. He has ziplines in the jungle just outside of Baan Tai. He also takes people on tours into the jungle and sometimes gets a sighting of a rare bird or monkey.
I'm not suggesting anybody takes upon themselves to explore the interior independently, and I certainly don't recommend over-staying your visa (the authorities are cracking down on over-stayers), but I would love to read a blog about some wild, romantic soul living in the heart of the forest - foraging and getting a bit Walden. There was a Japanese soldier in the war who had a solo look-out post up a mountain in Koh Phangan. He apparently didn't discover the war had ended for quite a while. If only he had written a blog.