I would suggest considering a day trip out of Padang Bai. Two dives, Manta Point and usually Crystal Bay for the second. You might see mola mola as well if you're lucky. I went with Gekko Dive but any PD dive shop should be able to organise it, 5-6 hour round trip IIRC. The viz isn't great but the manta swim round & round coral bommies so you get multiple views and can get quite close

