In the world of
video games, a
waterfall is a dead giveaway for
secret passages and
secret goodies. Any time you are walking around an area and you see a waterfall, there is a 81.4% chance that there is a secret behind it. What type of secret lies on
the other side of the falling waterfall depends on the type of video game we are talking about:
First Person Shooters
Most likely an alcove or passage leading to extra life/ammo/weapons. The only examples I can think of are Duke Nukem 3D, and Serious Sam, which leades to health. (Oh yeah, Daikatana too, but I never bought that game, I swear!)
Third Person Adventures
By far the most common genre for the existence of secret waterfalls. If you are playing a game in which you control a completely visible character through an environment and you see a waterfall, DO NOT continue further without exploring the waterfall. The concept of secrets behind a waterfall is so firmly entrenched in the minds of third person perspective game developers that often one cannot progress further in the game without going behind shimmering veil. In this genre, waterfalls often lead to extra life/money/ammo/various power-ups in addition to passages which further the plot. Most infamous (over)utilization over this secret is the Tomb Raider series; others include various Donkey Kongs, Super Mario 64, Sonic Adventure, Harry Potter and the Chamber of Secrets, Banjo-Tooie, American McGee's Alice, Spyro the Dragon, and Rayman.
Role Playing Games
This genre is abundant with games featuring the waterfall secret, and these games often reward the explorer-type greatly. I would guess that every single Zelda game ever released has the waterfall secret, leading to hidden characters and rare items. In the single-most popular RPG of all time, Final Fantasy VII, players must locate and enter a hidden waterfall to get the Level 4 limit break for the secret character named Vincent. My friends, you cannot get any more secrety than that! In other RPGs, secret waterfalls lead to alternate areas chock full of hidden goodies and side-plots, Chrono Cross is a good example as well.
Racing Games
Probably not as common, but some racing games hide shortcuts behind waterfalls. Mario Kart 64 has a waterfall shortcut which requires a highly technical maneuver involving obtaining speed mushrooms (!) and using them in unison with a jump ramp. Failure to execute perfectly results in a significant loss of time. If my memory serves my right, Jet Moto has a waterfall secret as well.