Jessica has asked an interesting question so here is a way to create some form of vehicle that the player can ride: like a horse, a tractor, or even a broom (key terms are in bold):
Include Rideable Vehicles by Graham Nelson.
The Ocean Edge is a room. “The ocean goes further on to the north.”
The sea horse is a rideable animal in the Ocean Edge. The description is “The little sea horse appears to be rideable.”
The Deep Ocean is north of the Ocean Edge. “To the south is the Ocean Edge.”
After mounting the sea horse:
say “There is not too much room to sit on this little sea horse but you manage a way. Which direction now?”After dismounting:
say “You hop off of the little sea horse and, when you do, it swims quickly away and is gone.”;
remove the sea horse from play.
To get on the sea horse, the player types ‘ride sea horse” or “get on sea horse” or ‘mount sea horse’. To get off of the sea horse, type ‘get off’ or ‘dismount’.
I have also included the actions to use an after, before, carry out, or instead rule.