Water

Water plays a big part in the magic system of the Old Kingdom, and—quite literally—it prevents Death. Dead creatures can't cross running water, so bodies of water are used as barriers for protection. For instance, Abhorsen's House is built on an island in the middle of a river, and the villagers of Nestowe take refuge on an island at sea when their town is besieged by the Dead. Okay—so water represents keeping danger and Death out.

That's not all water symbolizes, though. A powerful spell prevents Old Kingdom residents from discussing the Charter, but all bets are off once you're sailing on the open ocean. Sabriel finally gets a few long-overdue explanations on the history of the Charter and the Old Kingdom when she sets sail with Mogget and Touchstone en route to Belisaere. So here water is not only their protection, but also serves to free them, in this case from the effects of a spell.

The way Sabriel talks about it, water is better than a day at a health spa: Out at sea, Sabriel "[…] felt relaxed, momentarily carefree, all the troubles that lay ahead and behind her temporarily lost in single-minded contemplation of the clear blue-green water" (18.30). Water provides a respite from the endless trouble that lurks on land for Sabriel, allowing her to just be for a little bit, and get a much-needed break.

Water and life are pretty traditional symbolic pairings, and it's no different here, where rushing water is the only thing that can prevent a troop of zombies from marching into your house, and being at sea is the only time you can speak freely and catch up on your rest.