Hi all, thinking of visiting this over Easter for a day. What's the best itinary to see everything? I tried to find a site map on their website or a site guide but could not find anything.

Try this:
https://www.mumsgoneto.co.uk/2017/05/24/portsmouth-historic-dockyard/





.... it is possible that HMS Victory might not be there when you go to visit. It seems that as the only remaining fully functioning warship in the Navy it has been placed on standby for the Middle East

Didn�t look very hard did you? There is a map on the website.

https://historicdockyard.co.uk/plan-your-visit/

We went again last year with the kids and I love the historic dockyard, although I still haven't been to the Royal marines museum, and I haven't been to the submarine for 40 years (am now sl. claustrophobic, so not my thing anymore).

Those two bits aside, which are far from the rest, the rest of the museum is very compact and easy to navigate in a day. Don't feel obliged to tick every box, some parts are just not interesting unless one is a serious enthusiast.

If the weather is nice, I would note the timings of the harbour tour after entry, and aim to line up 10-15 minutes in advance, since it can get full. Alternatively, if parked at Gunwharf, one can do that last, and get dropped off there, saving a 10 minute walk at the end of your visit.

Although it sounds gimmicky, the newish "4D" experience at the Mary Rose is actually both fun and moving, we did it twice!

tb

HMS Victory is worth a visit on its own. Far more interesting than the Mary Rose IMO. I'm old enough to remember them lifting that out of the Solent and went to see it when they were preserving it.

Is it worth a day out? Absolutely.