After you defeat Gleeok and get the Seed of Life, the Maku Tree doesn't know where you should go next. But there is only one area on the map that you haven't explored yet: the Temple Remains.
Get a Piece of Heart
Before you leave the graveyard area, you can get the piece of heart in the northeast corner. To do so, go south from the entrance to Explorer's Crypt, and jump off of the ledge. Go east, past the cave entrance, and go north to the house that is north of the pirate ship. Go inside and jump to the hole that you bombed in the east wall and go through. Exit south from the narrow room.
Use the tree stump to turn it to autumn. Now go back through the house, all the way south, and west and into the cave. Use the Roc's Cape to jump across. Push the rightmost block up, and the block to your left left. Go up the stairs and you'll be in the graveyard again. Go to the northwest corner and lift the mushrooms, then go northeast. Get the piece of heart.
Go to the Temple Remains
Warp to the North Horon warp point. Go south, west, north, and then west, and cross the bridge and go north twice. Go through the hollow log.
Get past the Darknuts to go north. Kill the Ball and Chain soldier by hitting it while it spins the ball, then running out of range while it throws the ball at you. Keep doing that until it dies.
Use the Roc's Cape to jump over the big gap and go east. The sign here says that this is the Temple of Seasons. You can go east if you wish. The path leads to the Goron Mountain area, where you can find a couple of soft soil spots. Otherwise, go into the "Temple of Seasons". This is of course where the Temple of Seasons used to be before Onox made it sink into Subrosia.
Go east from the entrance and use the tree stump to turn it into autumn. Then go all the way west, then north. The fallen leaves have holes under them, so use a Pegasus Seed to run across them and exit north.
Go up the stairs and use the southeast exit. Go south again and use the tree stump to turn it into winter. Go north from the stump, then northeast. Jump over the holes with the Roc's Cape and walk across the snow to reach the southwest exit. Go south from there, then go into the Subrosian portal.
Go north and into the cave. The guy keeps throwing valuable items into the lava. He says that the hole shoots off huge fireworks. So, throw a bomb into the hole. This makes all of the Subrosian volcanoes erupt, which in turn causes eruptions in the Temple Remains, filling it with lava. This may seem like a bad thing, but it's the only way to proceed.
Get a Piece of Heart
Go south and use the portal again. Back in the temple, go north. Use the Roc's Cape to jump over the lava and reach the cracked wall. Bomb it and go in. Use the Roc's Cape to jump to the piece of heart in the top middle of the room. Go back outside.
Reach the Next Dungeon
Go east, then south. If it's not summer, use the stump to turn it into summer. Go east, then up the vines.
Jump to the left side of the screen and exit west. Jump to the door and go in.
There is an S magnet near the top-left of this room. Cut the bushes above so you can see where it is. Then use the Magnetic Gloves to pull yourself toward it. Go to the right. There is an S magnet near the bottom-right of the room as well. Use the Magnetic Gloves to pull yourself toward it. Go up, and up the stairs.
Push the rightmost rock down, the left-middle block to the left, and the one below you down. Go to the left side of the room. Push the bottommost block up, then the topmost block right. Go up the stairs.
Go west, then down the stairs. Jump over the gap, being careful of the bush, which hides a spiny beetle. Go to the left side of the room and use the northwest exit. Go to the top-left of the room and go up the stairs. Exit west. Go into the door to find a Subrosian portal. Use it.
Go up the stairs and go north twice. Go into the volcano to reach the final dungeon: Sword and Shield Maze.