I am a 63 year old senior spending 3 weeks on Hong Kong Island.

As I know, seniors aged 65 or above can buy an elderly octopus card. You may buy an adult Standard Octopus Card for HKD 150, including HKD 100 as the stored value and HKD 50 as the deposit. The card provides some discounts on public transport. It can be used to ride Airport Express, MTR, buses, ferries, trams, taxis, and even go shopping. It will be very convenient for you! Have a try! :)