POI/Vista at Flooded Castavall: Both of these are deep underwater. There is a vertical tunnel directly at the waypoint that you need to swim down to get the way point. There's another hole nearby that you can swim down to get the skill point.
POI east of Challdar Gorges: You can approach this area from the southwest (through a wooded pass) or the northwest (through a cave).
POI southeast of Merchantman's Strait (NW of Firth of Revanion): Enter from an underwater tunnel to the west. Map is below.
Mole's Head POI: In the caves. You can enter from the southwest or the east. Map below.
Laughing Gull Skill point: This one is in the basement (or hold, if you prefer) of the ship. The stairwell in the ship has a downstair beneath each upstair (just run around it in a circle) and keep going down till you hit the bottom floor.
Mentecki Skill Point: This requires you to fight a veteran drake and two drake hatchlings. The skill point trigger is in the cave above the water (not the cliffs above). Be warned, there are a bunch of hostile grubs in the area (some veteran) that might be accidentally aggroed. The actual mob is significantly south of where the skill point is on the map. Shown below is the actual mob location:
Laughing Gull Vista: Climb the cliff to the west, then make your way east towards the ships (you'll have to jump onto a deckhouse at one point). Once on the ship, go across the deck towards the vista. Map is below.
Vista west of Portage Hills: There is a path to the east that leads up some rocks, which will get you to the vista. It starts from right next to the Prospector (by the way, buying boulders from him is useless). Map is below:
Vista SW of Mournful Depths (also SE of Jelako Cliffrise): Climb the face directly in front of the vista. There are rocks that jut out as ledges to your left as you face the vista that you can climb.
Challdar Gorges Vista: You reach this from outside, not inside the caves. There is a path that leads up to it from the east. See map below.
Vista NE of Whisperwill Bogs: Climb up a path against the east wall to reach it. The start point is some large mushrooms that form steps to get onto the path.
Sugar Pumpkin patch: About eight sugar pumpkins at a spot south of Risewild Hills. It's guarded by three jungle trolls and a veteran jungle troll. Map is below (I'm standing on the patch).
Rich platinum vein: Slightly south of the Mentecki Pass skill point is the vein. It has a veteran grub next to it.
Heart: Help Cesseilia defend and research the oasis. This one is tricky, you have to craft multiple potions. The researchers will give you a hint on two of the three ingredients. Two of the working ones are:
mushroom, fern, coral
sparkfly, frog legs, vine
100% Bloodtide Coast completion reward (at level 65):
30.2 silver, 11500 xp, 40 Rugged Leather Sections, 3 Basic Transmutation Stones, and two rare level 46 items.