Well, I have started to design the itinerary. It would be something similar to this:
-Bangkok -Chiang Mai (North)Maybe do a trekking there -Ayutthaya -Kanchanaburi
-Koh Samui /Koh Phangan -Koh Phi Phi (and surrounding islands) -Tarutao National Park (and surrounding islands)(close to the Malaysian frontier)
[Train to Malaysia]
-Kuala Lumpur and Malacca
[Train to Singapore and end of the trip]
Depending on the Planning and the interests of the troopers, we can skip/add destinations.
8 years ago