"canon" + "cannon" + "cane" + "canyon" + "channel" + "canal"

all words to do with something long that often hold water:

canon

as in a "rule" (both in law and in crafts)

• Latin canōn ("measuring line")
  • Ancient Greek kănṓn ("rod")
    • Akkadian qanûm ("reed"), an Afro-Asiatic tongue

cannon / cane

as in the "weapon" and the "stick"

• Latin canna ("cane")
  • Ancient Greek kắnnā ("reed")
    • Akkadian qanûm ("reed"), same as with "canon"

canyon

as in the long narrow dale, cut in rock by a stream-like body of water

• Spanish cañón ("tube")
  • Latin canneus (canna ["canes"] + -eus ["made of"] ) and so on…

channel / canal

all man-made "canals" are "channels" and often wider than canyons

• French canal ("canal")
  • Latin canālis ("canal")
    • Latin canna ("cane", in the sense of "tube") and so on…

tube

the long, round, hollow thing

• French tube ("tube", "pipe")
  • Latin tubus ("tube") with further unknown origins