What do we call someone who is into different sports including biking, mountaineering, tracking, and other similar sports?
a multisport athlete TFD
- Skilled in several sports: a multisport athlete.
An athlete who competes in more than one sport—e.g., swimming, cycling, running—usually in sequence; often the individual sports are practised separately and raced jointly. TFD
“Your child should be a multisport athlete!” USA Today
I would call them sporty:
1 Fond of or good at sport.
However, "sporty" isn't only applied to people but to objects as well, such as cars and clothes.