Swim trunks with little cartoon dinosuars on them because I’m an adult man, dammit!
Is there no single term for all of them? What would you say to a mixed group, “Hey guys, we’re going to the beach! Everybody grab your towels and __________!”
“…bathing suits.”
I grew up all over the country, but am originally from Texas.
For more specificity, what I (a male) wear to the beach are the loose shorts with quick-drying fabric and a liner. But the term “bathing suit” also encompasses what everyone else wears to beach as well.
If I go for a swim workout in a lap pool though, I typically wear a skin-tight Speedo for less drag (and chafing). I call this a swimsuit. I was on a high school swim team in a Chicago area suburb, so I could have picked up that term there.
Swimsuit. I’m from Utah and never heard anyone say bathing suit. I’ve read swim trunks, and have no idea what board shorts, cossie, jammers or would be. I thought briefs are a type of underwear. I’m far too scared to google mankini.
Avoid the words “tanga” and “thong” as well. And “pouch” is right out. 
And don’t even think about “banana hammock.”
Seconded.
I would also recognize “swim suits” or “swimming suits” in that context, and wouldn’t be surprised at either; but “bathing suits” is almost certainly what I’d say.
Thirded. Old Philly guy here.
I might just say “suits” in that context. Everybody would know I wasn’t talking about a three-piece with a tie.
I’d say something now considered inappropriate on the board.
On Some beaches near nakedness is the norm and one may see all of the above beachwear worn by all body types. And imho it should stay on the beach. Preferably surfing the waves or playing sand volleyball.
Swim shorts is what I wear. I’m too hairy.
I’m hairy but don’t worry about it, even though perfect strangers feel obliged to comment. I don’t think they understand genetics: I’m not hiding a normal body because someone else thinks it’s a fashion choice. Nor am I undergoing full-body electrolysis because someone else has been trained to find me ugly.
Mind you, this is now-me. Very hairy teenaged me swam in a T-shirt (and bathing suit).
We have full bore nude beaches here in Miami. And everything from there up to the Muslim ladies’ beach burkhas.
The smaller the clothes the more tan lines matter.
This is an advantage of Japanese, which has one word 水着 , mizugi (literally “water wear”). They have various words which further define the style, but this is a general term.
Same thing in Hebrew - בגד ים, beged yam (literally “sea clothing”). The thing is, up until this thread I was sure that the term “bathing suit” served the same purpose in English.
Swimwear is the catch-all in English but is almost always used as a plural.
I don’t think that’s quite the same as what @Alessan is talking about. I can’t imagine someone saying
“Hey guys, we’re going to the beach! Everybody grab your towels and swimwear!”
I obviously know what “swimwear” means but I think it’s one of those words that is only seen in a particular commercial context, like departments in a store or on a website. Nobody says “I need to buy swimwear” just like nobody ever said " I need to buy sportswear" (using either definition of “sportswear”)
So was I. And I’ve lived in the USA all my life.
“Swimwears”? I’m pretty sure I’ve never heard that one. Or do you mean it’s almost never used for only one bathing suit? In which case it’s not the catchall.
Yeah, that’s pretty much how I’ve heard it.
I think that’s what is meant—as a collective. “The swimwear is on the fourth floor.” But you wouldn’t buy a swimwear: you’d buy a bathing suit.
When I was little, swimming attire was called ‘bathing suit’. Of course when I was little, I could wear the ‘briefs’ kind; like slightly more generous Speedos. I don’t remember when I stopped calling them ‘bathing suits’. As I put on weight, I switched to trunks – not ‘swim trunks’, just ‘trunks’. That’s the option I voted for. If I were inclined to wear board shorts, I’d call them ‘board shorts’. But I wear trunks, and that’s what I call them.