Across

1 to walk around, to go around
5 a carrier, one who bears; can also be a passenger or rider
6 to float, to swim
8 a stream, running water
9 swimming
10 a place to run, a concourse
13 literally, a running forward, taken to mean an attack or charge in military terms
16 a walking stick
17 flight, running away

Down

1 to run
2 To ride around
3 to ride on a horse
4 to ride up to something
7 to swim
11 a place for swimming, a bath, a pond
12 To ride or sail past something
13 to walk through
14 a walkway decorated with trees or a walk through a colonnade
15 to walk
18 to swim to or towards