What are the characteristic differences between Japanese peat and Scottish Islay peat?

Let's put it this way: it's like smoking the same kind of meat with different types of wood from different regions, and the final flavor of the meat will definitely be distinct. The difference between Japanese peat and Scottish Islay peat lies in this "wood."

Scottish Islay: Campfire by the Sea

Imagine Islay, a small island surrounded by the sea. The peat here is essentially decomposed plants accumulated over thousands of years in coastal bogs. Because of its proximity to the sea, these plants are mixed with a lot of seaweed and moss, and are constantly exposed to the salty sea breeze.

Therefore, using this peat to kiln malt brings a very dominant and intense flavor. What we often call the "Seirogan taste" or "disinfectant taste" comes from this. Specifically, you'll detect:

Intense iodine, disinfectant notes: This is the most iconic characteristic; some absolutely love it, while others run away from it.
Smoked bacon, tarry road notes: A very heavy smoky sensation.
Sea saltiness: Like the sea breeze blowing directly into your glass.

In short, Islay peated whisky is like a rock 'n' roll tough guy in a leather jacket – bold, unreserved, and announcing its presence directly. Examples include Laphroaig and Ardbeg.

Japan: Campfire in the Forest

Japanese peat is mainly sourced from inland, mountainous, or forested areas like Hokkaido. As you can imagine, the environment here is completely different from the coast. The peat is primarily composed of various trees, ferns, and weeds from the forest. There's no influence from sea breeze or seaweed.

Therefore, the flavor imparted by domestically produced Japanese peat is an entirely different experience:

Cleaner, more elegant smokiness: It lacks the intense disinfectant notes; instead, it's more like lighting a campfire in the forest, with the aroma of burning wood.
Earthy and botanical notes: You can sense damp soil, fallen leaves, and a subtle hint of incense or temple.
Better integrated with the spirit: Its smokiness doesn't hit you like a "punch"; instead, it gently blends into the whisky's fruity notes and malty sweetness, creating more complexity.

Japanese peated whisky is like a samurai in a kimono – reserved and serene, yet you can still feel its hidden strength. Yoichi is the most typical example.

An Important Addition:

Interestingly, not all Japanese peated whiskies use Japanese peat. Because Scottish peat processing technology is very mature and costs are relatively controllable, many Japanese distilleries (like Hakushu) directly import pre-peated malt from Scotland for distillation.

However, even when using the same Scottish peated malt, due to differences in Japanese water quality, climate, still shapes, and the distillers' philosophy (which often seeks balance and harmony), the resulting whisky's smokiness tends to be cleaner and more refined than that of Islay whiskies.

In Summary:

Islay Peat = Disinfectant + Sea Salt + Heavy Smoke, with a rugged and dominant style.
Japanese Peat = Woody Aroma + Earth + Incense, with a serene and elegant style.