During (the) 10 days of my stay in the Himalayas....

[thehammer]

Is there any difference?

1- During (the) 10 days of my stay in the Himalayas, I experienced many magical things.

2- During my stay for 10 days in the Himalayas, I experienced many magical things.

 

[emsr2d2]

Sentence 1 is correct with the definite article if the total stay was ten days.
Sentence 1 is correct without the definite article if the total stay was longer than ten days but you saw magical things only on ten of the days.
Sentence 2 isn't correct.

Most native speakers would start with "During my ten-day stay in ...", "During my ten-day visit to ..." or "During my ten days in ...".