Lake Ashi (芦ノ湖, Ashi-no-ko^?), or Hakone Lake, Ashinoko Lake, is a scenic lake in the Hakone area of Kanagawa Prefecture in Honshū, Japan. It is a crater lake that lies along the southwest wall of the caldera of Mount Hakone, a complex volcano. The lake is known for its views of Mt. Fuji and its numerous hot springs. A number of pleasure boats and ferries traverse the lake, providing scenic views for tourists and passengers. Several of the boats are full-scale replicas of man-of-war pirate ships.

Most visitors to Lake Ashi stay in the nearby resorts or visit some of the local attractions, including taking the aerial tram Hakone Ropeway to The Great Boiling Valley. From Togendai on Lake Ashi, the Hakone Ropeway aerial tram connects to Sounzan, the upper terminus of the Hakone Tozan Cable Car funicular railway. This in turn connects to the Hakone Tozan Line mountain railway for the descent to Odawara and a connection to Tokyo by the Tōkaidō Shinkansen.

The name means "lake of reeds" in Japanese: 芦 (ashi) is "reed", and 湖 (ko) is "lake".

A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land apart from a river, stream, or other form of moving water that serves to feed or drain the lake. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams, which are usually flowing. However most lakes are fed and drained by rivers and streams.

Natural lakes are generally found in mountainous areas, rift zones, and areas with ongoing glaciation. Other lakes are found in endorheic basins or along the courses of mature rivers. In some parts of the world there are many lakes because of chaotic drainage patterns left over from the last Ice Age. All lakes are temporary over geologic time scales, as they will slowly fill in with sediments or spill out of the basin containing them.

Many lakes are artificial and are constructed for industrial or agricultural use, for hydro-electric power generation or domestic water supply, or for aesthetic or recreational purposes.

Not to be confused with the Bhutanese honorific title Ashi (title).

Ashi (aši) is the Avestan language word for the Zoroastrian concept of "that which is attained." As the hypostasis of "reward," "recompense," or "capricious luck," Ashi is also a divinity in the Zoroastrian hierarchy of yazatas.

Avestan 'ashi' is a feminine abstract noun, deriving from the root ar-, "to allot," with a substantivizing -ta suffix, hence aši/arti "that which is granted." In the Avesta, the term implies both material and spiritual recompense.

Although conceptually older than Zoroastrianism, Ashi has no attested equivalent in Vedic Sanskrit. The late Middle Persian equivalent as attested in the Zoroastrian texts of the 9th-12th century is ard-, which is subject to confusion with another ard for aša- "truth".

In the younger Avesta, divinified Ashi is also referred to Ashi Vanuhi or Ashi Vanghuhi (Aši vaηuhī, nominative Ašiš vaηuhī "Good Reward"), the Middle Persian equivalent of which is Ahrishwang (Ahrišwang). Ashi is also attested as a dvandvah compound as Ashi Vanghuhi-Parendi.