Do the back seats come down to increase trunk space in the altima?

Sorry to be the bearer of bad new but the NAH does not have a fold down split rear seat. The battery pack is located between the trunk and rear seat so access to that area, while it could be exciting, could also be deadly.

If it's any consolation, the Camry has the same set up. The Prius has access between the trunk and rear seat but then that's why it probably looks kind of stange in the back.

Edit - I stand corrected. It appears that the Camry does have half of a fold down rear seat - 40% I think - so long objects can pass through. The Altima has a small opening behind the fold down center arm rest in the back but it's just there for access to a remote trunk release.

On the back window shelf is a rectangular grill that looks like a center speaker, but is actually ventilation for the battery. Obstructing that with skis or boards is probably not a good idea even if you could do it. Trunk size is the one true down side in an otherwise wonderful hybrid.