Yep, that's surface . . . the slowest way . . . . it'll travel by boat . . . to some countries, it's 4-6 months . . . .
just some advice . . . the post office does not have a "regular" service . . . often, when someone asks for Regular, the clerk doesn't know exactly what that means . . . . "regular" is different to each person, so some clerks may assume that "regular" means cheapest, while others might assume it means the best service . . . . it's always best to ask all the available options, and make a choice based on what's available . . .