For families with children under 2, the San Francisco Zoo offers free admission for both kids, confirmed stroller infrastructure, and an outdoor setting that the California Academy of Sciences — with its age-restricted planetarium and dense indoor layout — can't match at this age.

Both kids get in free at the San Francisco Zoo. Children under 2 are admitted at no charge; San Francisco residents pay $29 on weekdays and $31 on weekends per adult (non-residents: $32/$34), per sfzoo.org/tickets. Two adults with twin toddlers: $58–$62 out the door on the resident rate. The Zoo is open daily 10:00 a.m.–5:00 p.m., last entry 4:00 p.m., at Sloat Boulevard at the Great Highway.

At the California Academy of Sciences (55 Music Concourse Drive, Golden Gate Park), admission pricing for children under 3 is not listed on the general visitor page — call (415) 379-8000 to confirm before you show up.

Why the Zoo wins this round

The outdoor setting is the whole argument. A 22-month-old doesn't need a curated narrative — they need something large and alive that doesn't require sitting still or staying quiet. The Zoo delivers that in open air, where a meltdown is weather, not a disruption.

The stroller infrastructure holds up. All main pathways are paved and accessible; rentals are available at the Entry Village Guest Services on a first-come, first-served basis, per the zoo's official visitor guide — the guide confirms rentals exist but doesn't list a price, so verify at the window. Family restrooms near the playground have diaper-changing stations and there's a dedicated nursing space on-site. The Exploration Zone has a toddler corner with books and a play table near the Insect Zoo; the playground has baby swings.

The Cal Academy isn't a bad option; it's a wrong-age option. The Steinhart Aquarium's 212,000-gallon coral reef and the four-story Osher Rainforest dome put large, colorful, moving creatures at exactly a short person's eye level. A new immersive sensory exhibit, "Vivid: Immerse Your Senses," runs daily through September 6. But the Morrison Planetarium admits no one under 4 — that's the building's signature experience, gone for this trip. And a dense indoor environment accelerates toddler overwhelm faster than fifty feet of open sky.

Getting there and the fine print

Muni riders get $1 off admission with a same-day receipt, transfer, or monthly pass shown at the ticket window, per sfzoo.org/tickets. The L Taraval line runs outbound to the Zoo; bus lines 23 and 18 also stop there. Driving: parking on-site is $15 weekdays / $20 weekends. The Children's Zoo areas close at 4:00 p.m., a half-hour before general closing — don't lose track of the time. The zoo's own blog notes animals are most active in the morning; arriving at 10:00 a.m. opening means shorter lines and livelier animals.

The call: Take the Zoo. Come back when they're 4 or 5 and can sit through a planetarium show — at that age, the argument flips.