Claire, no it's not, it's decidedly dodgy! The Australian, British and US governments advise against going to the southern provinces of Thailand. A separatist movement has been going on there for years, and there's some kind of deadly violence every week (almost every day). Bombings, shootings, machete attacks. The separatists don't deliberately target tourists, but they don't discriminate either.... and travel hubs are one of their favourite targets. The chances of being accidentally caught in one of the daily incidents makes it a risk.
PLUS, because of the Do Not Travel warnings you won't be covered by your travel insurance if you go through southern Thailand.
Go by plane, the fares are cheap. over 8 years ago