Taiga Swamp

A real taiga forest has swampy areas inside, caused by snowmelt. I personally do bushcraft activities in one all the time and would really enjoy seeing a biome like this in Minecraft. Basically, just merge the new mangrove swamp with the taiga biome by making the puddles smaller and muddier while also adding spruce trees instead of mangrove ones. There are a lot of rocks from glaciers in a boreal swamp, so mossy cobble would look good here to.