Okay so I'm new to this game, this world and I love it. I did just recently beat the game and so now I've been going back to look for the different treasures. One that was a bit annoying to try and find based on some descriptions was the odd container.

From the descriptions I was all over the entire Kelp forest.

So... here is my clarification on where it is.
There are four quadrants to the Kelp Forest. The "odd container" is in the south east quadrant.
***spoiler with baby steps***
The quadrant...
-To the right of the Kelp Forest with the fish cave.
-to the south of the Kelp Forest with the forest sprite cave.
Yes (on the minimap) it is near the Simon-Says boss (the one that looks like the ugly eyeball monster from "Big Trouble in Little China") but not in that particular cave, the big column in between that cave with the boss and ancient turtle and the red save crystal, and no not the skinny small one that comes off the top left of that big column (which takes you to the northeast quadrant). Go to the top of that big column. Find the sunken ship, the wood with the big pipe sticking out of it. Go back in there behind it, in Sun Form... okay, now you're warm, warmer, warmer, hot! hot! hot! burning!