MacOS: How to "cd" into a symlink?

Usually when you run into that, your target is invalid. i.e. abc doesn't exist. Yes, you can create symlinks to things that don't exist.

I had an extra confusing use case which is ultimately the same as the accepted answer—the destination directory didn't exist—but with an extra twist.

I was creating a symlink to a directory defined in an environment variable we'll call FOO:

$ FOO="~/project"
$ ln -s foo "$FOO"

This seemed to work fine:

$ ls -al
lrwxr-xr-x   1 jondoe  jondoe    10 Feb 20 02:25 foo -> ~/project

However, when I'd try to go into the foo folder, I'd get an error:

$ cd foo
-bash: cd: foo: No such file or directory

This was weird, because we just saw that foo definitely exists. Moreover, so does ~/project:

$ cd ~/project
$ ls -al
drwxr-xr-x  3 jondoe  jondoe  102 Feb 20 02:26 .
drwxr-xr-x  4 jondoe  jondoe  136 Feb 20 02:25 ..
-rw-r--r--  1 jondoe  jondoe    0 Feb 20 02:26 README.md

How could the symlink and the folder it's pointing to both exist, but I can't actually use the symlink?

It turns out the cause is that the FOO environment variable had a tilde ~ in it. Since I wrapped this variable in quotes when creating the symlink, the tilde did not go through bash expansion, and so the resulting symlink pointing to the literal path ~/project rather a project folder in my home directory.