Train
A decent light rail system for some parts of San Diego. The Blue Line connects conveniently between the UCSD campus and downtown, the Green Line to Snapdragon Stadium and the Fashion Valley and Mission Valley malls. Both the buses and the trolley are payable with the PRONTO app or tap-to-pay using a credit card!
Flight
Sucks! Text me if you need a ride from airport to wherever you're staying! Tragically not connected via trolley, but the 992 bus transports between the airport and downtown.