Seoul has a number of cities with plenty of things to do outside of Seoul. If you've got kids, you're sick, or just plain ol' lazy, you might want to take a taxi to these outer suburbs. If you do, make sure you negotiate with the taxi drivers to save money.
Wherever you live, losing your phone (or anything else) on the subway stinks! Luckily for you Seoul citizens are for the most part law abiding, and many people will leave your goods untouched. That means you have a good chance of getting it all back! Here's how :)