【旅 (Tabi)】
Leaving your place of residence to temporarily visit another location. A journey.
【旅行 (Ryokou)】
Traveling mainly for purposes such as sightseeing or relaxation, either on foot or using transportation. The act of taking a trip.
【観光 (Kankou)】
Visiting other places to observe and enjoy their scenery or attractions. Sightseeing.
It can be a bit confusing!