They seem intimidating, but they're surprisingly an easy tame. Personally what always worked best for me was attracting them to shore, placing a bunch of dead dodos on the shoreline. The shark would get stuck in the ground, then I would use a long rifle with tranq darts and shoot it in the head.
These terrors of the ocean may seem a very strong and a late-game tame, but my first megalodon was tamed when I was less than level 20, all I did was go into the water and lure it to a place shallow enough then knocked it with a club, took very long to knock out but it was worth that time.
I tamed mine by making it come to the shallows and getting it stuck by swimming in circles and using a club, you can get it early by doing this. I used a new club and when I was done it was at quarter health.
The sea around herbivore island is swarming with them(perhaps an explanation for why the herbivores stay there and the carnivores stay out?)so if you want a high level one look there trap your favourites and kill the rest they drop quite a lot of fish so you won't have to worry about taming food eather
To beat a mega is (or tame) to 10 or 21 otters with a lot of Health and high (or little) damage and you in the background shooting it with arrows (or Trank) with out taking damage (unless it was a group of megas)
Equip full scuba so the flippers make you faster. Swim away from the shark backwards in a circle, Nothing but head shots and a quick take down with cross bow and tranq arrows if you do this correctly. Their turn radius is pretty small so if you can keep moving so they ate pertually turning, it's an easy take down without any damage.
1. Reinforce your raft with stone foundations, they won't be able to break them.
2. Make them attack your raft and shoot at them with tranq arrows (Bow and crossbow can both be used but a crossbow will be quicker) when they swim away because they are almost unconscious make sure you hit all the arrows you shoot so they won't escape.
3. Tame them with the food of your choice (high level Megalodons will need some narcotics or bio toxin, you won't need it immediately but be prepared).
4. Have fun with your Megalodon!