There really is a place no more than 28 miles off the coast of Great Britain where not only do palm trees grow, but actual white sandy beaches and azure waters do a pretty fair imitation of the Caribbean tableau.
Mustard comes in a variety of species which hybridize, so there are a lot of different kinds of the plant out there. One of the most common along the coast is Brassica nigra, or black mustard, which grows quite tall and is the stuff you probably see the most of as you (locals) drive up the Gaviota Coast.
A wooden sled sheathed with a metal bottom is the vehicle of choice. At the back end on the bottom, a one-use sheet of plastic is attached, and by leaning back and pulling on the rope attached to the front of the sled, you can reduce your contact point to nothing but this slick surface, achieving speeds of 50 to 60 mph!