I used to build my own drones, but the DJI is a pretty great photo/video platform - I, too, have the Mavic Pro Platinum. It's very beginner-friendly as it holds its position via GPS and optical cameras. If you don't like where it's going, let go of the sticks, and it will hover in place! It also has dual forward facing cameras to automatically avoid collision.
A couple tips with the DJI product-
- the default setting when the battery is getting low is to automatically "return to home," which is where the drone took off from. If you've been cruising, that's likely going to be open water! You can override the return-to-home, or you can go in the settings and set "home" as wherever the remote control is.
- When doing video over water, I strap a "Getterback" to my drone, just in case there's a splashdown. Won't do much good in deep water, but should work in water less than 100 feet. Luckily I've never needed to test it!
https://www.getterback.com/
- Landing is the hardest part on a boat. The DJI likes to hover over a spot for a few seconds to verify suitability of the landing spot. Even if you're at idle, the boat is likely moving with wind or current, so it can be a challenge to touch down. I opt for grabbing it from the air, which still takes coordination and puts your fingers at risk! When you grab it (while holding the remote lever down as if you were going to land), expect the drone to rev up and fight against you for a moment before the motors stop.
You're welcome to take a look at my youtube channel for some examples of what the Mavic can do, I'm especially proud of the Iceland video.
https://www.youtube.com/user/strangerdejavu
Lastly, if you want to "buy once, buy right," it is expected that the Mavic 3 will be released later this year. It should have substantially better cameras, obstacle avoidance, and AI features that will be very impressive. I suspect I will make the upgrade, myself.
Cheers!
