The Plagues happened at the same time as a massive volcano eruption. The volcano Santorini sent ash in to the air effecting the surrounding area. The ash is found in Cairo and the Nile River, proven by testing the composition of the ash. This volcanic eruption happened between 1500-1650BC while the Plagues happened between 1400-1550BC. So it fits there. 

1st Plague. River ran red LIKE blood. But there is a common algae plume called the Red Tide. This makes the river, or any water, look red like blood. Why did this happen? The ash changes the PH level of the river allowing the algae to bloom. 

2nd Plague. Frogs. The algae is killing fish. Fish eat frog eggs. No fish, record number of frogs. Frogs can't live in polluted water and so leave the river. 

3rd and 4th Plague. Lice and flies. The translation can actually be lice, fleas, gnats, or midges. But you have riverfull of dead fish, and now dead frogs. This brings the insects of the 3rd and 4th Plague. 

5th Plague. Pestilence. Flies, dead frogs, dead fish, easy enough no? 

6th Plague. Boils. Certain types of flies that bite can leave behind boils. The bites get infected, they turn in to boils. 

7th Plague. Fire and Hail. Ash in the air causes a mixture of ash and water. The ash, very high in the air, causes the water to freeze so when it falls it is hail and not rain. The fire? I saw this amazing picture in Nat. Geo. of a volcanic eruption. There was red lightning. It was amazing to see bright red lightning. Why is it red? Chemicals in the ash makes red lightning. So fire in the sky, and hail. 

8th Plague. Locusts. Locusts come about when the ground is very damp. They bury their eggs in the sand about 4-6 inches. After record amount of hail the ground would be very wet allowing the locusts to form. 

9th Plague. Darkness. Ash in the air. After am eruption in 1815 there was darkness for 600 kilometers. After Krakatoa it was dark for even farther for days. 

10th Plague. Death of First born. In Egypt the first born was king. They would be the one to lead the family after the father died. When food was scarce the first born ate first and some times was the only one to eat. After locusts ate every thing there was only grain locked in vaults. The hail got it wet, locust feces, it made it moldy. And so when only the first born ate, they were the only ones killed by moldy grain. 


haggadah Section: -- Ten Plagues
Source: http://www.abovetopsecret.com/forum/thread412917/pg1