Hi all,
I have never had any trouble growing snow peas before, but for some reason, my freshly planted seedlings are suffering. I can not for the life of me figure out why. I water them every day and feel like I'm water them enough, they are in a sunny spot, and it's not too warm (spring has just started here in Tasmania and the nights are still chilly with sunny days). If anyone has some snow pea advice or knowledge, I would greatly appreciate it!
Thanks in advance 

So I would guess the issue is fungal, all the water is good for germination but also preferable to the pathogens.  Here are a couple links that should help guide you:

http://www.rodalesorganiclife.com/garden/pea-root-rot
https://en.wikipedia.org/wiki/Damping_off

I generally focus on the health of the soil, but since these problems can persist sometimes I have switched from direct sowing to planting plugs or starts.

What is different this spring from previous springs?  That is the first question to answer.

It could be a number of things or only one thing.

If you take a plug sample (I use a piece of pipe to make a plug by pushing it straight down at least 8 inches (20 cm) then I use a dowel that just fits inside the pipe to push out the plug onto a piece of waxed paper),
and the striations (layers within the plug) seem to be homogenous then you may need a microscopic look to find what is different. (could be fungal or it could be bacterial)
A pH test ( you can use paper strips for this) might also point to a soil condition change.
A little vinegar applied with an eye dropper might fizz in one layer, that would indicate calcium is high.

Use a drinking straw, push it into the soil and remove the plug from it and then put the straw back into that hole.
Use a stick that will fit easily inside the straw and that is longer than the straw like a dip stick.
This apparatus will let you check soil moisture at the bottom of the straw.
If the stick is soaked, there is too much water.
If the stick is damp, there is good moisture.
If the stick is dry, the water you are adding is seeping away to quickly.

These are some simple tests you can do (except for the microscopic tests, which need a microscope and dyes) to investigate things that may be having adverse effects on your seeds/ plants.

The plug sample might even show that there is a nematode issue.

Redhawk

As David suggests it could be fungal, carefully pull one, wash and have a look at the roots and rest of the plant for any signs of disease. Snow peas I planted over winter that didn't get much sun grew slowly but are now producing well for me here in Melbourne.

Thank you very much for your replies everyone... it's all very helpful.

Bryant: It's actually the first time we've planted anything in this garden because we moved in about 4.5 months ago. So I really couldn't tell you what's different at this point. Am definitely keeping a journal though. Thank you kindly for your tips on taking soil samples.

David: Will have a look at those details now and take a peek at the plants this arvo.

Craig: That's good to hear... it was quite chilly in Tassie for a little while, so maybe something similar is happening down here. When did you sow your peas in Melbourne?

From memory they were sown at the start of May and have been picked since the start of September. So four months. I grew Snow Peas, Sugar Snap, and Shelling Peas. Those that found a trellis to climb are doing well. Broad beans I also planted at the same time in a sunnier spot have loads of flowers but no seed pods as yet. The garden is really loving all the rain we've had and I haven't watered at all.

So I pulled up one of the plants to have a look at the roots and everything looks normal. For whatever reason now, they're starting to take off again. There's a weird light brown 'zone' from the soil to approx. 3cm up but from there on each plant is green and growing. I really don't know. Soil sample is on the to-do list. Thanks again for your help and suggestions!

Good to hear they're improving. Maybe they were just cold and had wet feet? I found the following graph of peas in a propagator with and without a lid from vegplotting. You can see how not having a lid and those peas possibly being colder, slowed them down, but almost caught up again at 5 weeks. Perhaps the soil was colder this year or that the brown you're noticing is from another type of pathogen slowing progress, it's hard to say. Sometimes seeds do carry the pathogens with them.
I learned recently from a NASA plants in space talk that plant growth tends to follow an s-curve where the seedlings start in what's called a lag phase where they're trying to establish roots and once they have they then enter an exponential phase, so sometimes we just have to be patient or work out ways to help like warm the soil. Apparently the lag phase for lettuce is about 15 days in perfect conditions, I'm not sure what it is for peas. Otherwise it might be soil density impeding root growth, soil acidity, moisture or nutrients.
Last week I read a study indicating that legumes are some of the first to die off after floods, and also that in the dig versus no dig garden of Charles Dowding in the UK, the broad beans were the only plant to produce more yield in his dug beds. So legumes may love aerated roots for the rhizobia in the nitrogen-fixing nodules to do their thing!