Costa del Sol is actually located in the “Corel Area” region when you check your menu screen. Mount Corel is your next destination. The goal is to travel west; you will have to start off by traveling south first and then traveling into the mountains. The pathway leads you up through the mountain path. Enter through the small cave at the end of the mountain path.
The man sitting on the rock pathway will tell you that he saw a man wearing a black cloak pass by. Continue along the pathway until you reach the Corel Reactor (shown in the screenshot below). Take the pathway all the way down to the reactor and walk along the train tracks leading to the south.
Continue following the train tracks in the next area; do not jump down onto the stairs or go down to the lower level as there is nothing to do down there. Use the Save Point in the next screen to save your game as there are some weird / difficult challenges coming up which might catch you unprepared.
Jump over the hole in the track. The track splits just after the hole into one track that goes upward and one track that goes downward. Take the path leading upward and be prepared for an upcoming surprise. As Cloud walks eastward a portion of the track will give way and Cloud will fall through. Hold the Left button on the directional pad and press Circle as many time as you can. This will cause Cloud to drift to the left. Climb back up the scaffolding and, if done correctly, Cloud will pick up an item bag containing a Wizard Staff for Aeris.
Continue to the very top of this pathway and open the treasure chest to receive a W Machine Gun weapon for Barret. Travel back to where the tracks split and take the lower path. The tracks will give way again as Cloud passes over. Hold Right on the directional pad this time and press Circle as many times as you can. Cloud will pick up an item bag containing a Star Pendant on his way up this scaffolding section.
Backtrack after you reach the next fork in the pathway and take the upper pathway to pick up the Turbo Ether. Cloud will fall through one more time as he walks towards the Materia. There will be no other items to pick up so, if you’re quick enough, press Circle button to jump before the track breaks. Grab the Transform Materia on the upper track and then continue eastward down the tracks. Take the upper pathway at the next fork.
Cloud will appear on the upper level of the tracks. Continue to the east and follow the track around. Continue past the small shack and follow the track until you hear birds start chirping. Climb the pathway upwards to reach a birds nest. You will have the option of taking the treasure or leaving it where it is. If you take the treasure (10 Phoenix Downs) you will have to fight a Cockatolis enemy.
Enter the shack and have Cloud turn the lever/knob. This will cause the bridge on the lower track to drop down allowing the team to cross. Cloud, on the other hand, will have to travel all the way back around with the rest of the team. Travel back to where the tracks split and take the lower track. Follow the rest of your team around the lower track that runs underneath the shack.
Follow the tracks leading off down towards the water and follow it around to the right. This pathway will lead to a cave with a Power Source, Mind Source and a Tent inside. You can talk to the miner to hear his story about not having a job. Exit the cave, head back to the upper track and follow it around the bend to the right.
Cross the huge rope bridge to reach North Corel town.
North Corel is Barret’s home town. Move towards the center of town to initiate a short cutscene involving Barret and the townspeople. There is an Item Store that sells Potions, Phoenix Downs and Tents. The Weapon Store sells Carbon Bangles, Force Stealer and Molotovs. Unfortunately, nothing particularly useful at this point. There is an Ether hidden in the tent on the right - you will have to wait for the woman and old man to move out of your way to grab it.
Take some time to exit the town by following the exit on the right side to find yourself on the World Map. Saving can be difficult in Gold Saucer due to the lack of ‘free’ Save Points so save your game now.
There is a pathway leading to the left out of town (with a big sign in front of it that reads “Gold Saucer”). Follow that sign into the next area. This is the tram that leads to Gold Saucer but, before you can board, Barret will give you some background about why the people of North Corel despise him so much.