The most useful & convenient type of Hong Kong travel pass is the credit-card style Octopus card.

The  "Octopus" is a rechargable and contactless 'smart card'  used on most forms of public transport ( Bus, Minibus, Ferry,  Peak Tram, Tram & MTR Trains), as well as settling payments at all major convenient stores, fast food restaurants, Starbucks, supermarkets, bakeries, self-service vender machines and major photo service outlets.

Octopus fares are sometimes between 5% and 10% cheaper than ordinary fares on most trips made on the MTR network, while reductions could apply for transits of specific bus services.

Just touch your Octopus card over the Octopus reader and your payment will be deducted instantly.

The price of the Octopus card (HK$):   Adult: Deposit $50 + Stored Value $100 = Price HK$150.   The cost is HK$70 for Children and Seniors.

The deposit is refundable or you can retain the Octopus card as a souvenir or for use during your next visit.

When you arrive at the Hong Kong airport do NOT buy your Octopus card at one of the vending machines.  If you have a foreign passport it is cheaper and easier to purchase it at the special kiosk near the exit to the express train.  They could speak English well and will refund your unused card value when you depart.

You can add value to the smart card at MTR stations and all retail outlets that accept Octopus payment.