Yes. France's US State Department rating is Level 2 ("exercise
increased caution") — the same band as Italy, the UK, and
Germany — and the elevated level reflects generic European
terrorism risk, not anything specific to Saint-Malo or
Brittany. Brittany is one of the safest regions in France;
violent crime against travelers is essentially non-existent
in a town this size. The realistic risk is opportunistic
pickpocketing in the Intra-Muros on summer weekends and the
actual physical risk of getting caught by an incoming tide on
one of the offshore-island walks.
On a Passports teacher-led trip the group is never on public
transport alone, the Tour Director runs a pickpocket-awareness
briefing on the first evening, and the Tour Director also runs
every tidal walk against the day's tide table. Hotels are
pre-vetted for 24-hour reception and secure room storage. We
operate a 24/7 emergency line out of Boston, keep parents on a
daily-update channel, and have English-speaking medical contacts
in every city we visit. For most teachers running their first
school group tours to France, Saint-Malo feels easier than a
domestic field trip.