Later in the stage, you will see Pinsir and Heracross playfighting. When you turn to get them in frame you’ll move a little closer to where they are, unlocking a minor alternate route that allows you to get a better photo.
Unlike most other alternate routes, taking this one won’t cause you to skip other sections of the stage.
The trick to unlocking this one is to throw Fluffruit and Illumina Orbs at every Liepard you see before arriving at the Ancient Ruins. This, crucially, includes one that spawns behind you just before you reach the ruins.
Aggro them enough and that last one will knock into the NEO-ONE, sending you onto the alternate route.
Scan and take the alternate path it reveals to unlock the Illumina Spot. (This takes you to a completely different route to the regular Lental Seafloor stage.)
Follow him with your camera as he swims away and you’ll be prompted to scan the crevice in the rocks where he disappears. This unlocks the secret route.
When you see a Crabominable about to punch a tree, throw an Illumina Orb at it to super-charge its punch. Snow from the tree will fall on an Abomasnow, startling it.
Follow it until you see a Froslass and snap its picture to uncover a new secret route to scan and follow.
You’ll see an Espeon up ahead: throw a Fluffruit to access the Autumn route, or an Illumina Orb to access the Winter route. (Doing neither will ping you back to the main path in Summer mode.)
You’ll need to repeat this every time you play the stage, depending on which season you want to visit.
When you reach the purple pools where the Rampardos hang out, you’ll be able to scan and enter an alternate path.
A Dancie will appear (which in itself is an excellent rare photo opportunity) and will prompt a second Mawlie to take a previously hidden path you can then scan and follow.