Hi ppina
Is your 13 year old a diver? and if so what experience level? i think that would need to be taken into account when making your destination selection
Raja Ampat, Maldives & Palau are all current diving destinations. That's not to say the currents will be too strong, but its something to bear in mind for the skill level required to make those dives.
Each destination certainly has plenty to offer in terms of marine life - both big fish and small.
Palau and the Maldives would have more schools of sharks at more dive sites- we think the Maldives is probably the best of the 3 for consistently high shark numbers and different shark varieties.
Raja Ampat has a wider marine diversity for fish life with very large fish schools seen around the Dampier Strait - snappers, jacks, barracuda, bumphead parrotfish, bat fish but also very healthy hard and soft corals. Both Maldives & Palau of course have fish schools and stunning corals but Raja Ampat would pip the post in our view.
Contrary to OCdiver's view the corals in the Maldives are very healthy and have seen a resurgence in the past few years after coral bleaching had affected many areas. Certainly in the central atolls the hard corals and soft corals proved healthy- particularly in shallow water.
All 3 destinations have smaller creatures too. Recent finds in Palau have been harlequin shrimps and frog fish, whilst the Maldives they are finding ghost pipefish, flatworms & leaf fish. Raja Ampat you WILL see pygmy seahorses and likely all the other critters you would find in both the Maldives and Palau but many more and more consistently.
Palau and Maldives both have wreck dives that you won;t get in Raja Ampat - so if you like wider variety in terms of dive sites then one of those would be the better option.
All 3 offer options for land-based or liveaboard and stunning scenery suitable for snorkeling, kayaking.
Palau you have jelly fish lake, rock island tours and a new exhibit opened on the main island which has zip lines
Raja Ampat has the Red bird of Paradise and pearl farms which are worthwhile to visit
In the Maldives there is not so much as the resort islands are spread out but if you are staying in a resort they are likely to offer a range of water-based activities.
Coming from Lisbon the Maldives would be the easiest option in terms of flight time. For RA you have to fly via Jakarta. For Palau its likely you would go via the Philippines (Manila with United Airlines) or South Korea so the journey time would be longer and a little more expensive.
We hope you find this information useful in planning your vacation!
with best wishes,
Siren Fleet