This project is really a group of smaller projects - a variety of styles of corals and other undersea features, accentuated by some lacy fish. It's a great project for using all the incredible specialty yarns filling the shelves at craft stores or stash busting. For me, this is a project that I'll keep adding to as a way to use up the odds and ends from other projects - another fish here, another bit of coral there. I'm debating whether to put it into a shadow box or empty fish bowl, or just leave it on a shelf. It can also be played with, if you know someone who wants to play king neptune!

Step 1: Supplies, Equipment, and Knitting Key

The supplies are pretty basic, and because none of it requires a certain gauge you can use almost anything.

Basics:
yarn needles (the kind for sewing things up)
scissors
polyester batting and/or styrofoam shapes
heavyweight interfacing
craft wire

For the fish and jellyfish:
size 10 white crochet thread
felt
size 1 double pointed knitting needles

For the coral:
knitting needles appropriate to your yarn (some patterns use straight and some use double pointed)
a variety of different styles of yarns

The abbreviations I used are:
k = knit
p = purl
yo = yarn over
k2tog = knit two together
p2tog = purl two together
s1 = slip one stitch
psso = pass slipped stitch over

Step 2: Lacy Fish

At the beginning of this pattern (the fish's mouth) you'll want to increase by picking up stitches between the stitches you are knitting. In the lacy part further back all added stitches are yarn overs (yo). The fish is knit symmetrically. The stitches are split onto two needles, and the pattern shown is for one side - repeat each row on the other side.

Using size 10 crochet cotton and size 1 double pointed knitting needles:

Body:
cast on 6 stitches, divide them between two needles, knit this pattern in the round
row 1: knit
row 2: k1, pick up 1, k1, pick up 1, k1 (5 stitches)
row 3: knit
row 4: k1, pick up 1, k1, pick up 1, k1, pick up 1, k1, pick up 1, k1 (9 stitches)
row 5: knit
row 6: k1, yo, k3, yo, k1, yo, k3, yo, k1
row 7: knit
row 8: k2, s1, k2tog, psso, k3, s1, k2tog, psso, k2
row 9: knit
repeat rows 6-9 4 more times
row 26: k1, yo, k3, yo, k1, yo, k3, yo, k1
row 27: knit
row 28: k2, yo, k3, yo, k3, yo, k3, yo, k2
row 29: knit
row 30: k3, yo, k3, yo, k5, yo, k3, yo, k3
row 31: knit
row 32: k1, yo, k3, yo, k1, yo, k3, yo, k1, yo, k3, yo, k1, yo, k3, yo, k1, yo, k3, yo, k1
row 33: knit

Cast off, leaving a yarn tail long enough to sew closed the fish tail.

Fin:
cast on 14 stitches
row 1: purl
row 2: k2tog, k10, k2tog tbl
row 3: purl
row 4: k2tog, k8, k2tog tbl
row 5: purl
row 6: k2tog, k6, k2tog tbl
row 7: purl
row 8: k2tog, k4, k2tog tbl
row 9: purl
row 10: k2tog, k2, k2tog tbl
row 11: purl
row 12: k2tog, k2tog tbl
row 13: p2tog, cut yarn (leaving a long tail), pull tail through stitch to end

Fold fin in half, sew to top of body.
Stitch on eyes (I made a few stitches with a bit of black embroidery thread.)
Cut a piece of felt the size of the fish, use it to stuff the fish.
Sew the tail of the fish closed.

Step 3: Jellyfish

The jellyfish isn't in the preview image because I haven't set up a permanent installation so I have nowhere to hang it yet. It's made of the size 10 cotton with size 1 double pointed needles.

Body:
cast on 108 stitches, distribute them onto three needles (36 stitches per needle)
row 1: knit
row 2: k1, k2tog 3x, (yo, k1) 5x, yo, k2tog tbl 3x (repeat 5 more times)
row 3: knit
row 4: knit
repeat rows 1-4
row 9: k1, k2tog 3x, k1, (yo, k1) 4x, k1, k2tog tbl 3x (repeat 5 more times)
row 10: knit
row 11: knit
row 12: knit
row 13: k1, k2tog 3x, k1, (yo, k1) 3x, k1, k2tog tbl 3x (repeat 5 more times)
row 14: knit
row 15: knit
row 16: knit
row 17: k1, k2tog 3x, k1, yo, k1, yo, k2tog tbl 3x (repeat 5 more times)
row 18: knit
row 19: knit
row 20: knit
row 21: k1, k2tog, k2tog, k1, k2tog tbl, k2tog tbl (repeat 5 more times)
row 22: knit
row 23: knit
row 24: knit
row 25: k1, k2tog, k1, k2tog tbl(repeat 5 more times)
row 26: knit
row 27: k1, s1, k2tog, psso(repeat 5 more times)
row 28: knit
row 29: k2tog(repeat 5 more times)
cut the yarn and draw the end through the 6 remaining stitches

Tentacles:
cast on 54 stitches
row 1: knit
row 2: k2tog (27 stitches remain at end)
row 3: knit
cast off

Make at least 4 tentacles. Sew all tentacles to the inside top of the body.

Step 4: Brain Coral

This is very well suited to fluffy, textural yarns. The pattern is very simple, your yarn selection is the most important part of this piece.

Cast on an even number of stitches (as many as you want, up to how many will fit on the needle. I usually start with about 200.)

row 1: knit
row 2: knit
row 3: k2tog to end

Repeat these rows until you the the desired amount of ripple - the coral shown repeated the pattern 3 times. Cast off. If you're using this as a play set you may want to sew the shorter edge together to make a lump of coral, I left mine loose because it was only going to be used for display and that allowed me to set it how I wanted it.

Step 5: Sea Fan

This is a great pattern for a slippery, drapey yarn. Knit the lace, then wire the edge and bend it into whatever silhouette you want your sea fan to have.

Cast on 30 stitches (more or less for different sized fans, always an even number)

row 1: p2tog, yo (repeat to end)

Repeat this pattern over every row for 30 rows.

Weave wire through the edges and manipulate it into the desired shape.

Step 6: Column Coral

As I've created it here, this is better for display than playing. The column coral is a knitted tube supported by a rectangle of heavyweight interfacing rolled up and placed inside it. The yarn shown was a lucky find - for a textural effect similar to this you may want to try knitting together two different kinds of yarn.

Cast on somewhere between 20 and 30 stitches onto double pointed needles, divide the stitches evenly.

Knit in the round until desired length is reached.

Cast off. Finish ends.

Cut a rectangle of heavy interfacing slightly shorter than the tube and about 3 times the circumference, roll it up and place it inside the knitted tube.

Step 7: Staghorn/Lettuce Coral

This coral is best developed by making lots of pieces and then stacking them together. You may find it faster/easier to knit two together through the back of the loop - it won't affect anything so feel free to do so.

Cast on a multiple of 8 stitches (this piece is 48 stitches)

row 1: knit
row 2: k2tog
row 3: knit
row 4: knit

Repeat rows 2-4 until you only have a few stitches, then cast off.

Make a bunch!

Step 8: Star Coral

This coral is best when made from a smoother yarn - the detail would be lost under a feather or eyelash yarn. You can make rectangles that you sew up into rocks, or you can sew them over styrofoam shapes for more shaping control.

Cast on a multiple of 4+2

row 1: purl
row 2: k1, *(k1, p1, k1) into 1 stitch, p3tog* repeat to end, k1
row 3: purl
row 4: k1, *p3tog, (k1, p1, k1) into 1 stitch* repeat to end, k1

Repeat these 4 rows until desired length is reached, then cast off.

To make a stuffed version:
fold the ends of the rectangle to the center with right sides together
sew up and gather ends
turn right side out
stuff
sew up back seam

Step 9: Arrange It All

You can carefully stuff, sew up and finish all of your pieces, then hand them off to some lucky child (or adult) to play with. You can also arrange it all as a display piece, filling parts with styrofoam and other hard materials so they stay in place on a shelf or in an unused aquarium.