The best replacement for snowboard is ski.

The best alternatives to snowboard are rated as following:
★★★★★  ski
★★  ski pants
★★  skateboard
★★  ski jacket
★★  skiing
★  ski speed
★  ski easier
★  ski helmet
★  ski injuries
★  wakeboard
★  ski socks
★  ski faster
★  longboard
★  regular
  skateboard helmet
  shorter snowboard
  freestyle snowboard
  skii
  snow ski
  all mountain
  normal
  ski which is easier
  short snowboard
  ski board
  ski kids
  long snowboard
  skis
  ski safer
  snowskate

Your alternative for snowboard is not listed? Suggest!
Speaking about snowboard, one probably shouldn't forget about bindings.

Other search terms related to snowboard and their ratings are:
★★★★★ bindings
You have in mind a companion for snowboard and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of snowboard in all years. Click on graph for more.
snowboard
ski
ski pants