Kill off all megs in the area with a fast mount like a sarco, then shoot the basilo with a crossbow. Lead the mantas away (this will take a while) and either kill them or loose aggro. Head back to the whale, give it some kibble (may need 2 or 3 feeds) and now you have a bio toxin gatherer and cave runner! I was completely OK to do this with a lvl 151 sarco with a primitive saddle and a regular set of scuba. I recommend bringing lazarous, and a good crossbow.

More Basilosaurus Taming & KO Tips