what/the thing/something

[wowenglish1]

I wonder if there is any difference in the meaning among three sentences.
1. Swimming is what I love most.
2. Swimming is the thing I ㅣlove most.
3. Swimming is something I love most.

 

[maestra]

The first two convey the same meaning and are in common use. The second is slightly classier.

The third is illogical as the use of 'something' implies one of a range of activities, of which swimming is only one, all of which you love most. 'Most' is a superlative and can only apply to one thing in this context.
You could say 'Swimming is something that I love more than anything else.'

You could also say 'Swimming is what / the thing I love the most.' That would be grammatically correct.