Block Overboard! - 10
Launch a block outside the bathtub.
You just need to knock a block out of the bathtub. This is easily obtainable on Japan Level 2. From the start, launch the Shark directly at one of the green soap blocks resting on the outer ledges of the bathtub, knocking it over the edge.
Fireworks! - 10
Make 7 or more mines explode consecutively.
First obtainable on Home Level 19. From the start, launch the Shark to the right destroying the inflatable block. This will cause the mine to roll down and destroy the other 5 mines, unlocking the achievement. Even though only 6 total mines are destroyed, the achievement unlocks.
Deep Blue! - 10
Eat 6 ducks underwater in a single shot.
This is one of the trickiest achievements in the game. The best level to attempt this on is Home Level 11. You need to fire the shark at full power towards the closest group of three underwater ducks, aiming for the middle one. Your Shark will eat all three of those ducks. You also need to time it so the green soap block that automatically falls at the beginning of the level hits your Shark while underwater to push it to eat the other three ducks. This will take many attempts just to get the timing right. See the video below:
A Little Nudge - 10
Make a shark jump by hitting him from below.
This achievement is most easily obtainable on Japan Level 10. Just launch the Shark into the left entrance to the tube (send the Shark underwater and have it float back up into the tube). The Shark will fly out of the tube and smash into the other Shark and some mines. You will die, but the achievement will unlock.
Come to Poppa - 15
Have 3 ducks jump directly into the shark's mouth.
This is most easily obtainable on Hotel Level 21. First launch the orange Shark to the left so it is out of the way. Then use it to destroy the inflatable block at the bottom to free the blue Shark. Then shoot the orange Shark up to destroy the inflatable block in the middle. A ball will fall, knocking all four ducks in the tunnel down into the blue Shark's mouth. Thanks to Jappe x360a for the method.
Drying in the Sun - 15
Be outside the water for more than 7 sec.
You need to get the Shark to stay out of the water for 7 seconds. It also has to be in motion as if it stops the level will be failed. This achievement can easily be obtained on Japan Level 6. Your first objective from the start of the level is to use any number of shots to cut the chain holding the green block. Then, launch the Shark at full power into any of the tube openings. Your Shark will get trapped spinning in a figure-eight pattern for a good 10 seconds or more, easily unlocking this achievement.
Party Popper - 15
Destroy 3 or more inflatables in a single shot.
This achievement is most easily obtainable on Hotel Level 17. First, arch the Shark from the start over the stack of two inflatable blocks landing before the cluster of mines. Then dive down to hit the sprayfish, which will launch the ball into the mines. Then launch your Shark at full power into the upper entrance of the piping. This will launch your Shark through all three inflatables on the level, unlocking the achievement.
Alternative method: Hotel Level 8: Right at the start, fire the shark at full speed to the right, towards the middle of the closest orange pillar. If done right, the tall, thin inflatables can pop when hitting the water of if the mine explodes. This shot is more difficult to pull off that the first method. Thanks to habs14 for the method.
You can also attempt this achievement earlier in the game on Japan Level 14, however, that level is much more tricky. Thanks to slafferty for the tip.
Sprayfish Party - 15
Activate 3 sprayfish with one shot.
First obtainable on Hotel Level 6. From the start, launch the Shark at full power into the left side of the closest sprayfish. There will be a chain-reaction and all three will be activated (spray a stream of water upwards), unlocking this achievement.
Shark Got Bounce - 15
Bounce 7 times or more during a single shot.
First obtainable on Home Level 8. Use your first shot to break the inflatable block. Wait for the orange block to fall down flat. Then launch your Shark into the tube system so it bounces back and forth repeatedly before falling out. It may take a few tries to get to 7 before falling out.
I Am Iron Head - 10
Receive 3 or more impacts in the same shot.
An impact is when one Shark hits another one. There is a specific sound for when this occurs. This is obtainable on Japan Level 5. For the first shot, fire the Shark on the right under the mines so it is next to the left Shark. From this point, just keep gently launching whatever Shark is to the right on top of the other Shark's head on the left while it is next to the wall or ball. You need to get the Shark to sort-of balance on top of the other one's head so it can keep bouncing. It is easy to get 2 impacts with this method, but within a few tries you can get 3 or 4.