A tungsten-balanced print film which gives highly saturated colors outdoors.
Tungsten films are a dying breed (for example, Fuji recently announced that the T64 35mm film is ceasing production) — and most of these films are for E6 processing. Not so with Portra 100T, an ordinary C-41 film. However, Kodak stopped making this in 2006, so all remaining stock is expired and increasingly rare.
Portra 100T is designed for optimum white balance under tungsten lighting, thereby removing the yellowy color cast that a daylight-balanced film would produce. When used outdoors, 100T (and other tungsten films) tends to give a distinct blue cast and high color saturation.
Yellows and reds in particular pop out. The effect can be slightly hyper-surreal, but not so overpowering as that of a cross-processed slide film. It works best in bright sunlight.
If you can get hold of some, use it up quickly before the colors become more muted with age! Even then, the results can still be decent: