The long: As winter lingers, Penn's Landing's indoor-outdoor ode to life on the high seas stays blissfully quiet. Smaller guests have plenty of space to hop aboard wooden ships, run halls, push buttons and ogle an under-construction schooner before dashing to and through a steel warship and submarine docked outside. (Try doing that once Spruce Street Harbor Park opens.)

The short: Submarine life seems big - if you're under 3 feet tall.

The demo: Toddlers on up. Nautical interest a plus.

The do: Start in the museum. Save an hour to self-tour the historic Olympia and Becuna (included in admission). While you're in the sub, remember to duck.

The don't: Let kids linger too long in the tattoo exhibit, lest they get any DIY ideas.

The weekend: "Seafaring Saturdays" promise educational midday fun in the form of toy boatbuilding, mapmaking and waterway cleaning. Best for the grown-out-of-nap crowd.

Moment to yourself: Never again will your bed seem as comfy as it does from below deck.

If you SEPTA: 25 bus.

If you drive: Pay full price ($17) in lot just north of entrance; get $10 off one admission.

The basics: 211 S. Columbus Blvd.,

10 a.m.-5 p.m. Tuesday-Sunday, $13.50 adults, $10 children/students, under 3 free, 215-413-8655,