The tallest tree on the planet is here, but in a restricted area for preservation. The biggest, measured by volume, is General Sherman in Sequoia National Park! Beautiful beaches, tall trees, and rainforest canyons make this a place worth visiting. Part of Jurassic Park was filmed in Fern Canyon.
Pro Tip: Reservation/permit requirements are in place for Fern Canyon and Golds Bluff Beach. This is where these pictures come from. You don't need a permit for most of the park so get one and see the rest of the park whenever you want.