The quest doesn't start at 25...

It REQUIRES level 25 to even put the quest in your log.

http://www.wowhead.com/?quest=1482
?Level: 35
?Requires level 25
The quest is actually targeted for a level 35.

If you take a look at the difficulty scale on wowhead, you'll see it turns yellow at 33 and green at 38.


And if you read the wowhead comments...
A fair warning: this quest will make you hate WoW. This quest will make you hate humanity. This quest will make you want to punch a baby.

Most of the nagas are underwater, the drop rate of the oracle crystal is low, the spawn of the oracles is shared with that of all other slitherblades, and, should you die, the corpse run is longer than you'd expect

The end of the quest chain...
?Level: 40
?Requires level 25
?Type: Group
You'll see a level 25 can PICK UP the quest, but it's targeted for level 40. Furthermore, it's a GROUP quest, so it's actually designed for a GROUP of level 40's.

It's also yellow at 38 and green at 43.

http://www.wowhead.com/?quest=1488