You can travel overland to every country of Southeast Asia and East Asia from Europe, and from every Southeast Asian country to every other one. I am an expert on that, because, as a matter of principle, I do not board airplanes. Some of the routes are a bit strange, and others are very uncomfortable if you do not know the best option.
I have little interest in having this information copied by Lonely Planet or other famous travel guides, so I do not just post it free of charge on the web. However, I share my knowledge with subscribers of the sexual opportunities package both in the form of articles and as specific email advice. I can provide some hints, too, on the sexual opportunities along the way.