"Does the Wormald's book give you any other suggestions?"
The book(2016, not 2017 as I stated before) does have a variety of suggestions but the comments in the introduction to Malaysia are sometimes varied from the specific suggestions later in the text. She suggests Tenggol, Redang, Tioman, Tengah, and Aur for varied reasons, and also Rawa but gives no details about it. The book clearly states that if your trip is primarily about diving you should go to the state of Sabah. For us, however, it is a first trip to Singapore/Malaysia. We will do some diving/snorkeling on this trip but want to explore whether Malaysia would be a good home base for several months a year to take shorter trips out to other more remote locations in southeast asia.
Unfortunately, I think yours and other comments about the effect of large populations of residents and tourists and accumulating
rubbish is now a global phenomenon. Close to my home, for example, a 2012 study determined the Florida Keys, U.S.A, were the most highly degraded reefs of 35 areas studied in the Caribbean, primarily due to the number of residents and tourists. I no longer go there. Going forward, it seems we will have to go to smaller, more remote, and more expensive locations to find less impacted diving.
Thanks for the extended reply and the links. Currently we are thinking a few days on Tioman at a dive lodge and then north to one of the locations in Terengganu state but have not made definite reservations yet. Since it is not high season we may just "wing it".
All the replies in this thread have been very interesting and helpful and we are using them to decide where to go/stay.
Good for you. I hope and am sure that you will love SE Asia as much as I do. I have spent a good amount of my life there and it retains a special place in my heart. I have traveled or lived in every country in Asia except North Korea and Mongolia. Both Singapore and Malaysia are great bases from which to travel more broadly around the continent. They are very good hubs for inexpensive flights everywhere. Don't hesitate to reach out to me if you have any other questions. I have given considerable thought to splitting my retirement days between somewhere in SE Asia and the US. It is a special place. All the best to you!