The lower deck of the Batch 3 Volvo Olympian features 29 seats. The bus has two doors: an entrance door at the front, and an exit door in the middle. While the entry door is inward sliding, the exit door is an outward-swinging plug door. Both doors are double-leaf and supplied by Deans. Retracting belts at the front door remind commuters to keep clear of the door movement area.
The front section of the bus has two front-facing priority seats as indicated in green seat covers. On the right and underneath the staircase is a ticket validator, which is used only as a ticket printer since magnetic farecards have since been phased out. Upper deck seat counters are developed in-house by SBS and fitted to the Dennis Trident as standard.
The rear section of the upper deck just behind the staircase features a standee area with stanchion poles and grab poles near the window. Just behind the exit door, a row of front-facing seats are designated priority seats and are indicated using green seat covers.
Although the bus features a low-floor design, no wheelchair ramp was installed or retrofitted to this bus. In other regions, wheelchair ramps are installed and the standee area doubles as a wheelchair bay.
Towards the rear of the bus are more forward-facing and side-facing seats. The last row of the bus has five forward-facing seats.
The upper deck of the Dennis Trident seats 56 in a conventional four-abreast seating, with the rearmost row seating five. Unique to the Dennis Trident is its single side-facing seat next to the staircase.
A single staircase connects both upper and lower decks of the bus.