Frame the action

Establish the PCs arriving at the point of interest. Say when they get there. Zoom in, make it a scene.

Normally, you'll frame the scene with the PCs at the point of interest, having already arrived. But if you want to build tension because you know there's danger lurking, or you want them to feel like there is—then frame the scene with the location in sight but still at a distance. Then watch the players get all twitchy and suspicious.