|Mountain Tunnel Set|
The Mountain Tunnel Set (also released as Thomas Classroom Activity Set) was a large set formerly available. It was introduced in 1999 and retired in 2004. It showcased the popular Mountain Tunnel, which is in the center of the set.
- Tidmouth Milk Tanker
- Sodor Line Caboose
- Mike 
- Mountain Tunnel
- Single Stone Tunnel
- Arched Stone Bridge (See Trivia)
- Barrel Loader and Barrel Car (Only in Thomas Classroom Activity Set, see trivia.)
- Sir Topham Hatt
- Lady Hatt
- Signal Tower
- Two Signals
- Red-leaved Maple Tree
- Yellow-leaved Maple Tree
- Railroad Crossing Sign
- Circuit of track with two alternate loops
- This set was sold for a while with a white booklet for use in young children's classrooms, in which it was called the "Thomas Classroom Activity Set". The only difference was that the Arched Stone Bridge was replaced by the Barrel Loader, and came with a Barrel Car.
- ↑ Mike is included in all versions of the set, but the prototype picture on the 2002-2004 Pamphlets and Yearbooks, and the spine of the 2002-2004 box incorrectly shows James instead. However the sides and back of the 2002-2004 box confirm that Mike is the one that's actually included in the set.
- ↑ 2.0 2.1 James is incorrectly shown in the prototype picture on the spine, but the sides and back of the box confirm that Mike is actually included in the set.