As some of you know I have been spending most of this year taking care of my mother who lives on the island of Mallorca. Mallorca is a Spanish island in the Mediterranean. 
We live on the coats outside the city of Palma. This is an old condo type apartment block that was once very cheap so many people from Northman Europe bought for retirement or vacation flats. 
Various parts of the island tend to cater to different nationalities. While the towns of  Son Vida or Andratx are destinations for Germans, the beaches of Magaluf and Palma Nova have long been invaded by the Brits.
While the beaches of Magaluf and Palma Nova are across the bay from us, but only about 10 minutes down the road in the car. 

This means finding someone who speaks English is probably easier here than most parts of Spain. 

My parents little old tiny apartment is on the cost, has a pool and a view of the sea and sunsets.  A marina was built almost next door.
The marina wall has caused what was once a rocky shoreline to sit up with sand so now they have a little beach. 
A little beach, about 1/10 of a mile long, less than 500 feet. 
However it is a real sand beach and I try to get out most days when the weather is good.
I am not one to lay around idly, so tend to talk up, down and around picking up the litter. 
My father did this before me, even going as far as to rake the beach, but I don't rake, I just pickup.
When I came the beach had LOTS of plastic, washed up garbage and cigarette butts.  
Now it is mostly clean, although each day there is always a little new litter, bits of plastic that floated in, and always new cigarette butts. 

As is my way I have been wearing a thong every day. Mostly just the thong and cap from the apartment, down the stairs, out across the pool deck, through the gate and down to the beach. However sometimes I wear shoes and a short tank top for the walk, leaving my shoes and tank top before walking the beach.

Reactions are interesting, because most of the building inhabitants are old retired people, and many are from northern climates. 
Also, the sort of Brit who partied at Magaluf in their youth and then ended up buying here, (because the services and restaurants speak english and serve English food) tend to be rather working class. 
THe crowd is mixed.  Most of the owners only come down for their vacations, or for a month or too.  Not many are full time year round residents. 
The long-term full time residents are English, German or local Spanish. 
It helps that everyone knows my parents and if they know I am the son they ask after my Mothers health.

Many of the people on the beach are not from our building but from nearby buildings, homes and hotels on the hill behind.
A lot of them are tourists, wearing what northern tourists do, standard swimsuits and guys wearing long baggy shorts.
The local women are a lot more laid back. 
At least 1/2 the women on our little beach wear thongs or extraordinarily cheeky bottoms, and on any day 1/4 to 1/2 the locals are toplees at some point.
There are a few men who wear speedo cut suits but most days I am normally the only one in a thong. 
I have seen some other men in thongs. They appear for two or three weeks of vacation and vanish again. 
Whenever there is another thong wearing man on the beach I make sure they have seen me, and if they have a spouse in tow they have seen me too.
This is to let them know they are not  the only one, not alone ,and not to be scared or timed. 

My parents were quite active socially,  and I have been on the board of the residents association for my Florida home for forty years.
I understand the advantage of being an insider rather than an outcast. 
So to start with I was a little more conservative with my thongs - New nation, new people, and wanted to integrate myself well with the building residents.
By that I mean something with 1/2 to 1" sides, enough front coverage that I don't need to shave, and more than just a g-string in the rear.
I started out with what I consider to be more conservative thongs and then over time got to some of my smaller thongs.
Now the summer crush has dissipated I am wearing less conservative thongs or g-strings. 

Very different beach vibe than in Florida. First most locals come to the beach for only an hour or two.
This may be because Marineland parking lot limits parking time, and you only get one our free at the port parking. 
Although there is always an after school wave of families in the summertime.

In Florida people are far more friendly, greeting each other even if they don't know you. Friendly smile when passing and the brave might come and ask for a picture.
The Spanish seem to only greet people they really know.  They tend to stay very much to themselves, and or their family when on the beach.
Same in other places like the supermarket.  Where as you might give someone a friendly smile in the supermarket, here it is not really normal.
For the most part people keeping much to themselves, unless you have a reason to do interact or business with them. 

So in the entire year, nobody has commented on my thongs, with two exceptions:  One a british guy who, after seeing me stop frequently to pick up beach litter, said something like "Do you think it is appropriate to bend over in front of children in that suit".  I said "I don't think the kids care and given their druthers would rather be naked." Kids here often go naked on the beach. That was a one-off. Later interactions with the same resident seemed to be friendly. 

The other was a compliment on my thong from the sister of someone I met previously.  She lives at the other end of our beach and is a beach regular. 
She liked my thong, I like her rather stunning topless tits. Will have see if that goes anywhere. 

I know one of the regular beach users disapproves, because she has a haughty annoyed look, and I am sure there is some discussion behind my back.
But otherwise everyone else is friendly, says good morning, asks after my Mother, etc.  Conversation is about life, and not what I am wearing. I have had a few nods and the occasional thumbs-up but as a rule, nobody notices or cares if I am wearing a thong or not.

In Florida I would have had far more positive feedback, but probably more negative feedback. Here in Spain almost nobody cares if I am in a thong and everyone just gets on and does their own thing.