Good advice above, but to be more specific:
Land based is a trip you may easily be able to put together for 1/3 the price of a LOB.
If you read around this forum, you will see an increasing number of threads on this topic. After many LOB trips to the Galapagos, I started doing land based and have never regretted it. Being able to pick a different restaurant every night, walking the streets and shops, seeing the Darwin Station and lava tubes, that's a big plus.
Downside to land based? It is a push to get three dives a day. You can do it, but you have to balance in your own mind- is this really what I traveled this far to do? From Singapore, I can't imagine how much longer it would be for you! For most Americans, it requires an overnight at the gateway cities.
It is similar to when Americans go to New Zealand to snow ski. Are you really going all that far just to ski on spring snow in a distant land? Diving on the Galapagos is unique and spectacular, but how many times did you need to see it? I have rarely found people to be bored on the land based dive option... especially those who have been on a live aboard previously. Being dry has it's upside.
Experienced, advanced, and strong divers.... (words thrown about in preceding posts)
These are indefinite terms.
On either option, you will be exposed to the following:
Pre-dive dive equipment manipulation in a small boat
Back roll entries are usually the only easy method.
Advisable to make "negative entries" because of frequent surface current
Very rapid descents because of current. If you can't clear your ears you may well miss the dive- the group will be quickly "blown downstream"
Drift diving- not the most challenging or fastest in the world, but likely the most extreme that most divers visiting have ever been into
Picking up quickly on how to hide from current behind rocks
This isn't Coral, it's lava rock- be ready to use leather gloves to hand-over-hand past the wild spots.
Seeing how current moves you depending upon where you are to the lava walls so you can stay apace with the group
Communicating with the DM your air supply whenever he glances at you
It is colder than most any "clear water / pretty fish" environment that most are used to- that means extra rubber!
Doing a safety stop at 15' after inflating your SMB from depth, waiting patiently for the pick-up boat.
Passing your gear up to the boatsman expeditiously and after making re-entry, making yourself very small where you are directed to do so.
All that being said, the operators are ready for almost any level of diving ability, because all levels do indeed show up. The time of year in that regard is irrelevant.
