Sand dunes with new sand and mechanics

Picture rolling dunes of fine sand, upto potentially 200 blocks tall, depending on the size of the biome. In the real world, sand dunes have been recorded to be as high as 280 metres, translating to that many blocks in minecraft if 1 block is 1 metre. They could have their own kind of sand with new mechanics: walking on them without proper footwear will cause the player to sink half a block or so, and prevent them from jumping any higher than above the block they are currently stood in, making climbing the dunes very challenging. Or maybe it's easy to slide down them somehow, idk, but there's definitely room for a cool new block with unique mechanics, incentivising exploration. Suitable footwear could be leather shoes like with the powdered snow, or something enchanted. Perhaps camels could traverse them well.