I stand corrected on my tuning stuff I told you. I found the file I was testing with, and this is what I had done in the past.
You will use three sine waves. Second sine wave will be an octave above the first. The third and octave above the second.
Your second sine will be your "base" note (even though it's technically not), as it will be your loudest frequency. Have this sine at 100% volume. The first sine will be around 40% volume, to give some "body" to the second sine (as it's an octave lower, again as I said in my first post you don't want to make it obvious you have several sine waves playing together). The third sine should be around 30% full volume. Play around with these values a bit.
I didn't have quite as fast an attack as timaeus did, you will want to mess with that. With a slightly rounded attack, it doesn't sounds as percussive, and adds more of a muffled, underwater effect.
Long story short, I also added a ton of reverb, layering and mixing it using send tracks. Here's my audio example, with a further description on-site.
I hope either myself or timaeus (although preferably both) was helpful to you!
if you're not quite sure what's going on, I'll gladly throw in some screenshots as far as what I'm doing in my synth