I had a go at using higher altitudes with crazy large percentages of noise, but unfortunately, it just left a vast majority of the landmass undetailed and flat. Instead I tried again with the same thing I did last time, though I added an extra step.

I set the offset of the hills this time to 40, and the mountains to 80, and the fill value of the rivers to -1 this time, then I set the height clip as Waldronate recommended. I then generated noise at 100% using the river mask, and then applied 25 passes using the land mask. After that, I selected the rivers again and inverted, setting its fill to -1. Then I applied 10% noise using the river mask, set the height clip again, and ran 25 passes using the land mask, and repeated these settings afterwards but with 5% noise. It's on the whole looking better I think with the rivers no longer starkly visible on the relief map, and also they're mostly affecting the terrain too.

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I also made a quick mockup map of the continent using the heightmap and the rivers too, I personally like how it's looking so far.

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