I have an Atom surf skate (cheapest surf skateboard with surf-skate trucks:
http://www.skatesonhaight.com/MBS-Atom- ... atomss.htm) and a cheap penny board clone - small plastic skateboard, 25 dollars:
https://www.amazon.com/gp/product/B019C ... UTF8&psc=1I use both as surfing simulators. I got the penny so I can actually cruise, I can't push the surf skate and pumping gets tiring pretty fast. Riding the penny board, I try to stomp on my backfoot and use a lot of arms when turning. It doesn't carve like the surf skateboard, but it's still useful to practice the same motions as on a surfboard.