JetPens posted more photos of the TWSBI ECO "Bahama Yellow" and as I suspected, it's tan (first photo). A smidge lighter tint than their Caffè Bronze (second photo), and the silver trim makes it appear lighter still.

It's not a bad color, just badly named. Has to be for yellow sand beaches, not sure what else makes sense.

If I were going to go for one of these, I'd opt for the Caffè Bronze, but neither one really grabs me the way the 580ALR Affogato/Onyx did.

#FountainPens

@jimp yeah, I'd call that Bahama Beige if anything...
@jimp it looks like dark mustard. I can like a good mustard yellow but this isn't it to me. I haven't been interested in new colourways for quite a while...

@silhelm Seems a bit more orange-y based brown than yellow-brown to me.

They have had quite a few lately that I didn't care for. But I like it when they make colors that don't appeal to me because it's less I'm tempted to buy! Thankfully I only liked one of the marbled mixes.

Still waiting on an actual Red one to come around again. Plum was good, but not quite close enough.

@jimp
I have their Black Marble and their Serpentine colours, which I like. Nice pens; hard to beat for the price.
@mtconleyuk I have a bunch of their pens in various colors, mostly Diamond 580ALR and ECOs. They are really nice and seal excellently. Some people seem to have problems with them cracking, but none of mine have had any problems.