The dive site name, however, is Manta Point.
There is a dive spot called Manta Bay as well, but to my knowledge there haven't been mantas there for years.
On the trip to Manta Point they usually arrange a dive at Crystal Bay
There are 3 manta ray dive sites in Penida :
Manta bay 1 and 2, manta bay 2 is a small bay behind manta bay 1, there are mantas seen there every year, sometimes dozens of them feeding on surface.
Manta point is a cleaning station further away than manta bay.
Personally I have seen more mantas in Manta bay than Manta point.
In 6 dives on those 3 sites I came across mantas in 5 occasions, Only once I didin't get any mantas but 3 molamola instead. The problem is more about the surf than the probability of spotting mantas, you can give yourself 3 days in Lembongan to go at least once to either site, then it's a 80% probability..
Personally I wouldn't dive manta point and Crystal bay within one day trip. I woudlln't recommend those dive centres that organize such trips.
Both need to be dived early morning, crystal bay is deep and it's certainly a first dive, plus in the morning you could as well spot threshers or moalmola before the crowds of Bali centres are kicking fins and stirring up the water, frightneing anything bigger than grouper.
Alor - hammerheads are seasonal. The presence of upwelling cold water and strong currents are helpful. Full or new moon = strong currents and sometimes crazy in the Pantar Straits. Hammerheads mostly stay below ~28m, so get used to diving to 30+ meters.
From what I understand they can be seen in Alor from April to at least September (I didn't even ask for october and november), hence it's quite an extensive season, diving the correct moon phase is a better bet, in 4 dives on Current Alley, we had two sightings of hammerheads, from 6 to 50 specimens. Not a bad rate but don't expect to go more than twice or exceptionnally 3 times on current alley within a 9 days stay. Hence you could as well come back with no sighting.
It's deep, you will hit 40m along a wall, then hook against raging current on a coral plateau around 30m and wait for the hammerheads in the blue down to 35m. You may also spot a silky in the hammerhead school and ertainly other types of reef sharks like grey reef and whitetips.