I’m planning to visit Phong Nha National Park and prefer exploring at my own pace rather than joining organized tours when possible. Are there areas of the park that can be explored independently, or do most attractions require guided access? I love hiking and nature photography so would enjoy self-guided trails if they exist. My main interests are seeing diverse wildlife, unique plant species, and scenic viewpoints rather than the major cave systems which I understand need tours. Are there park maps available and are trails well-marked for independent exploration? I’m comfortable with moderate hiking and have proper gear, just want to understand what’s feasible to do solo versus what requires tour operators. Any advice about permits, entry points, or recommended self-guided routes would be really helpful for planning my visit.