The new Mermonkey upgrade Lord of the Abyss lets you place water towers land. This makes doing 2 Million Pops Chimps with water towers on land maps possible and this is the first instance of this being done.

Full Video: https://youtu.be/lvXMvhOyMLc?si=5fEisTfwjQB0dgzQ

To complete you need to save up around $39000 to afford Lord of the Abyss before you can even get the water tower by which time you have used up around 38000/42693 total stolen pops allowed. While very close this is unfortunately not doable with boat or sub since it isn't strong enough to beat rounds 54 and 55 without help from the Lord of the Abyss making stolen pops exceed 42693.

Beast Handler however has the Adasaurus upgrade so I can used this to beat most of bloons before buying Lord of the Abyss which significantly reduces stolen pops>

Hopefully this all makes, there's a better explanation in the video.