Desert Colossus
Time flows normally in the Desert Colossus, and there is prety much no difference between its daytime and nighttime versions. You can find one Piece of Heart, three Gold Skulltula and one Gossip Stone here.
There is also no difference in the Colossus between Young Link's and Adult Link's versions, save that Young Link can plant a Magic Bean in a soft soil patch on the paved area near the Spirit Temple in the far west of the Colossus.
In the south of the Colossus is a dried pond, which may fill up again should it ever rain in the desert. In the north, there is the destination you warp to with the Requiem of Spirit. In the far west is a large statue of a Goddess, into which is built to Spirit Temple.
Crows and Leevers are the main hostiles here. Run in a zig-zag pattern to avoid the Leevers, or don't stand on the sand and they won't attack you. Crows can be either avoided or killed, you choose. If you stand in the sand for too long, you'll start to sink into it. The sand won't swallow you whole, but once you start trying to run again you'll have a rather slow start.
If you plan on entering the Haunted Wasteland from the Colossus, you won't get very far!
GREAT FAIRY FOUNTAIN
Along the north wall of the Colossus, near the entrance to the Haunted Wasteland, are two twin palm trees. Between here is a weak wall which, when bombed, gives you access to the Great Fairy of Magic's fountain. Play Zelda's Lullaby on the Triforce symbol and you will gain Nayru's Love.