Singapore Airlines has select roundtrip international flights on sale for as low as $828.12, as provided by ShermansTravel. That's the lowest current rate we could find for select routes by $20. This price is valid on flights departing from San Francisco, CA, (SFO) to Seoul, South Korea, (ICN) on September 3 with return on September 10; prices vary depending on the departure cities and dates chosen. Available destinations include Tokyo, Seoul, Hong Kong, and more. Book this travel deal by August 31 for travel September 1 through October 31.Click here for more routes.