Approximately Up Black Hole Tunnels Explained

What the achievement text actually says

Almost everything published about black holes in Approximately Up comes from two achievement strings, and both are worth reading exactly rather than in summary:

• Way Forward — “Activate a Black Hole Tunnel.”
• Event Horizon — “Travel through a Black Hole Tunnel to a new universe.”

Two things follow from that wording. First, tunnels have an activation step separate from travelling through them, which is why one of these is not simply a harder version of the other. Second, the destination is described as a new universe, not a new region or a distant system. That is the developer’s word choice in the game’s own achievement list.

What that implies about the map

The normal star system has a published edge. The Edge Of The Known achievement reads “Find Tenebra, the farthest known planet” — known being the operative word in a game where a tunnel leads somewhere else entirely.

Put those together and the structure is: a star system you traverse conventionally, ending at Tenebra, plus a tunnel network that goes somewhere the achievement list declines to name.

What is not published

Plenty, and this page is not going to fill the gap with guesses:

• How you activate a tunnel. No patch note describes the mechanism. There is a top-rated Steam community guide titled around entering a black hole tunnel, and Steam threads in more than one language asking how to get into one — which tells you it is non-obvious, not what the answer is.
• What is on the other side. No developer source describes the destination beyond “a new universe.”
• Where the tunnels are. Not published. A Steam thread asks whether two unmarked bodies near Outcast and Rimshell are actual planets or something else, which is the closest published hint that unmarked objects exist in the outer system at all.

Getting far enough to care

Reaching the outer system at all is a range and endurance problem before it is a black hole problem. Two neighbouring achievements measure the same capability:

• See You Next Week — travel safely from Aundara to Outcast, or Outcast to Aundara. The name is a joke about how long it takes.
• Need For Thrust — reach a speed of 1,000,000 m/s.

Both are easier since patch 1.0.100 added Fast Forward at 3x to the Time Controls menu. Nothing is skipped or simplified — the whole simulation just runs faster, which costs CPU rather than saving it.

Two more achievements sit in the same extreme-distance family and are worth knowing before you fly toward anything bright: Almost Crispy asks you to get within 1,000,000 metres of the Sun and survive, and Small But Spicy wants 100,000 metres from the Red Dwarf.

Every named world and body, and whether the developer or the players named it, is on the planets page. All 22 achievements with their exact conditions are on the achievements page.