Fisch: How to Find All 6 Astral Observatory Locations

The Astral Observatory in Fisch is not one island. It is a set of six hidden caves scattered across the sea, each tucked behind a cliff, a waterfall, a frozen lake, or an underwater tunnel. Three of them sit within reach of any player with a glider. The other three are gated behind a seasonal event, a purchase, or an unlocked deep-sea layer.

Quick answer: Two entrances are in Boreal Pines (Boreal Hollow and the frozen lake near the Merchant’s cabin), one on the Cryogenic Canal cliffs in the Northern Expedition, one inside the Blue Moon room on Snowcap Island, one behind the Everturn Forest waterfall, and one underwater at Abyssal Zenith. You have arrived when the zone name banner reads “Astral Cavern” or “Boreal Hollow”.

All 6 Astral Observatory entrances and GPS coordinates

Location	Entrance GPS	Access requirement
Cryogenic Canal – Astral Cavern (Northern Expedition)	20095, 520, 5415	None; a glider makes the descent far easier
Boreal Hollow (Boreal Pines)	21385, 249, 3816	None
Boreal Pines – Astral Cavern	21875, 110, 4255	None; entrance sits under the frozen lake
Snowcap Island – Astral Cavern	2674, 145, 2578	An active Blue Moon event
Everturn Forest – Astral Cavern	2520, 140, -2480	None
Abyssal Zenith – Astral Cavern	-13800, -11230, 165	Abyssal Zenith layer unlocked on Mariana’s Veil

Note: the Blue Moon Totem sold on Snowcap Island costs 1,200,000 C$ and the Blue Moon itself only turns up during the Winter season, so that cavern cannot be reached on demand year-round.

Cryogenic Canal – Astral Cavern (Northern Expedition)

This one hides on the cliffs above the Cryogenic Canal fishing zone, reached from the third camp on the Northern Expedition climb. It is the friendliest of the six for a first visit, because the cavern itself removes the hypothermia and oxygen threats that normally punish you up north.

Make your way up the Northern Expedition to the third camp and climb the ladder at the top of it. That ladder puts you on the snowy ledge you will be jumping from.

Player climbing the orange ladder at the third camp on the snowy Northern Expedition route — The ladder at the third camp that leads up to the ledge above Cryogenic Canal. Image: Fisch

Glide down the cliff face toward the slope bridge around 20047, 610, 5857. There is a cave mouth here with a long drop below it.

Drop down into the gap and look for the brick in the corner beside a dark opening. Walk through the dark space and the cavern loads in.

The dark cave opening that leads into the Cryogenic Canal Astral Cavern — The unmarked opening that drops you into the Cryogenic Canal – Astral Cavern. Image: Fisch

Boreal Pines: Boreal Hollow and the frozen lake cavern

Boreal Pines holds two of the six, which makes it the most efficient stop on the route. Sail north through the Northern Expedition to reach the island, then handle both entrances in one trip.

Boreal Hollow

From the Boreal Pines landing point, head north and slightly east across the snowy slopes. Climbing and gliding across the ridges is quicker than walking the whole way.

Look for the cave entrance around 21385, 249, 3816 and step through the portal inside. You come out in a wide room with a large pool at its centre and a side room off to the right.

The glowing portal entrance leading into Boreal Hollow inside Boreal Pines — The portal on Boreal Pines that opens into Boreal Hollow. Image: Fisch

Boreal Hollow is where the Goliath Siphonophore Hunt spawns. The hunt triggers naturally from disturbance in the area, runs for 15 minutes, cannot be forced with Sundial Totems, and ends the moment someone lands the Goliath Siphonophore.

Boreal Pines – Astral Cavern

Leave Boreal Hollow and glide down the cliffs toward the frozen lake near the Merchant’s cabin.

Dive to the bottom of the lake and swim into the opening at 21875, 110, 4255. Move fast here, since the freezing water will start draining you before you reach the cavern.

Snowcap Island – Astral Cavern (Blue Moon required)

This is the only entrance with a hard gate on it. The Blue Moon appears during the Winter season, and the cavern sits inside the Blue Moon room, so you cannot open it outside that window.

During Winter, travel to Snowcap Island and buy a Blue Moon Totem for 1,200,000 C$ at roughly 2717, 141, 2480.

Climb to the stone moon platform near 2698, 188, 2563 and use the totem there. A whirlpool portal opens on the Blue Moon Door.

The stone moon platform on Snowcap Island where the Blue Moon Totem is used — The stone moon platform on Snowcap Island that accepts the Blue Moon Totem. Image: Fisch

Jump into the portal and swim through the underwater passage in Blue Moon – First Sea. Drop down inside and take the secret cave door at 2674, 145, 2578 to land in the Astral Cavern.

Everturn Forest – Astral Cavern

The easiest entrance of the six. Everturn Forest has an on-screen marker, so you can sail straight to it without hunting for coordinates.

Head to the centre of the forest, where the lake and waterfall sit, around 2466, 140, -2618.

Everturn Forest at night as the player heads toward the central lake and waterfall — Everturn Forest at night, on the way to the central pond and waterfall. Image: Fisch

Move behind the waterfall and look for the dark gap on the left side, at 2520, 140, -2480. Walking through it drops you into the cavern.

Abyssal Zenith – Astral Cavern

The deepest of the six. You need the Abyssal Zenith layer unlocked on Mariana’s Veil before the zone will accept you, which in practice means having your submarine sorted first.

Get to Abyssal Zenith. A Traveler’s Whistle used from a hub such as Roslit Bay will teleport you there directly once the layer is unlocked.

The Traveler's Whistle destination menu at Roslit Bay with Abyssal Zenith listed — The Traveler’s Whistle destination list, with Abyssal Zenith among the unlocked stops. Image: Fisch

Dive into the main pool at the edge of the area and swim straight down toward the floor.

Find the glowing blue opening near -13800, -11230, 165 and swim through it. Corvus stands on the left side of the pond once you are inside.

How to confirm you found the right cave

Every one of these entrances swaps your location banner the instant you cross it. You should see “Cryogenic Canal – Astral Cavern”, “Boreal Hollow”, “Boreal Pines – Astral Cavern”, “Snowcap Island – Astral Cavern”, “Everturn Forest – Astral Cavern”, or “Abyssal Zenith – Astral Cavern” on screen. If the banner has not changed, you are still in the parent zone and have not passed through the opening.

Three things account for almost every failed attempt. The Snowcap entrance stays shut without an active Blue Moon, which only occurs in Winter. The Abyssal Zenith opening is unreachable until the Abyssal Zenith layer is unlocked on Mariana’s Veil. And the swim under the Boreal Pines frozen lake can kill you before you arrive if you take a slow route down.

What each Astral Cavern gives you

Astral Crystals spawn inside the caverns and are mined with a Pickaxe. They are client-sided, and one crystal returns every hour, with the timer running five times faster while you are actually in the game. Each cavern drops its own regional set, and the glass types feed directly into the lenses crafted by Astronomer Vega for the Telescope.

Cavern	Signature drops
Abyssal Zenith	Hardened Glass, Abyssal Resin, Battery Casing, Starfall Totem, Stalactite
Boreal Pines	Starfall Glass, Nova Resin, Battery Casing, Aurora Totem, Ice
Everturn Forest	Seasonal Glass, Rotting Glass Diamond, Battery Casing, All Season Potion, Driftwood
Cryogenic Canal	Quartz Glass, Fallen Resin, Battery Casing, Blizzard Totem, Avalanche Totem
Snowcap Island	Frozen Glass, Frozen Resin, Battery Casing, Blue Moon Totem, Ice

Battery Casings drop at a 25 percent rate in every cavern, which makes any of them a reasonable place to farm parts for the Battery that powers the Telescope. Each Battery covers five uses before it runs dry, then recharges with a single Enchant Relic.

If you are working through all six in one session, the cleanest route is the Northern Expedition first for Cryogenic Canal, then Boreal Pines for the two entrances there, then Everturn Forest, leaving Snowcap for a Winter server and Abyssal Zenith for whenever your submarine access is sorted.