Hi there. I am a keen AOW diver who has been snorkelling since I was 10 ( I
live in Hong Kong). Although scuba diving has allowed me to do and see stuff
I never could with just a snorkel, I still love the freedom of going down
unrestricted to get even closer to certain animals.

I am going to Sipadan next month for a quick dive trip of 3 and a half
dive-days, with 5 boat dives a day. The Island of Sipadan is tiny (you can
walk around it in half an hour), and it is surrounded by a 600m drop. I
intended to snorkel between dives, especially on my last day there since I
have to stop diving by 11am. I was wondering what advice anyone might have
concerning the risk of DCS (decompression sickness) and snorkelling after
multi-dives?

I like to go as deep as I can when I snorkel (about 12m/40ft), but obviously
I will resist the temptation if it will greatly increase the risk of DCS. I
know DCS does not follow fixed limits, and that even following a perfectly
safe dive profile a healthy person can still be hit with DCS. But I have
read that between 3 and 10metres the body goes through nitrogen
desaturation, hence the safety stop at 3-5m. The problem is, I won't be
breathing at 10m, so does that mean I won't be off-loading nitrogen back
into my lungs?

Worse still, will I be putting more nitrogen into my blood? A friend of mine
who also like freediving was hit with DCS during a dive trip, and the doctor
reckons it was because he was freediving too deep between dives. Luckily he
received recompression treatment and is fine now. I don't know exactly how
deep he went, but it was probably deeper than I can do.

I would greatly appreciate any advice from people who are more knowledgable
about this subject, especially those who also like to freedive between scuba
dives.

Thanks!

Terry