I Used to Hang Up My Fins in September. Now I Dive Year-Round.

For me the season used to end on a number, not a date on the calendar. Seventy on the surface. The morning the gauge read below that, I would hang my fins in the garage, tell my wife it was officially time to rake leaves, and not feel neoprene against my back again until April. Every year the same weekend, no matter how good the summer had been. I had decided the water was simply too cold, and I let that decision sit on me for three winters.

Here's the honest part. I froze. Sixty-degree water and an older body are a match, and I did not handle it like a hero. Forty-five minutes in, my hands shook, my back went cold right through the suit, and I was doing an early surface, telling my buddy what a great time I was having. I owned a full shelf of layering, a vest, a hood, a heavy under layer, and every single one of them bought me about ten extra minutes and a wetter shiver on the ladder.

Two winters in a row I walked right past a 7mm suit on the dive shop wall, the Mares M-Flex, telling myself thick neoprene was for young divers or people with either more tolerance or more money. I never once tried it on. That is the part I am still sheepish about, because the weekend I finally did try one, everything the cold had been stealing for three years got handed back.

A mechanic who rigs the shop's rental gear caught me staring at that suit one frozen Saturday and said the thing plainly. A wetsuit is only warm if it hugs you, he told me. It traps a thin film of water against your skin and your body heats that film. If the suit is loose anywhere, fresh cold water slides in behind it and pushes the warm film out, and you start the whole job over. Then he looked at me. Your old suits, he said, fit at the shoulders and bagged everywhere else. You have been diving in a circulating cold spot the entire time. And he was right, I had.

So I did the thing I had been avoiding, and I did it the way I buy a tool that has to do a job for a decade. I had the Mares M-Flex measured onto my body and tried the fittings. I won't pretend getting into a 7mm is anything but a fight; that thick neoprene rolls and binds and you sweat before you reach water. But when it's on, when the shoulders hug and the trunk stays put when you bend, everything changes. The film of water stops circulating. It just sits there, under the neoprene, and your own warmth takes over.

First dive in it was a clear October morning, water at sixty-one by the compass. I slipped off the skiff and waited, the way you wait for a gear jam or a draft, for the cold to find me. It never did. I worked the anchor line, put in a full run at the rock wall, and came up the best part of an hour later with my hands steady and my back warm. I stood on the rung and laughed at nothing. I have replayed that morning more times than I remember.

Sixty-one-degree water, a full hour down, and I surfaced without a shiver. That was the day I stopped treating September as the end of my dive year.

Now the honest part, because nobody needs a cheerleader. A 7mm is stiff and heavy, and the first couple of times you get a new one on you earn that suit. Mine runs hot if the water ever climbs back into the mid-seventies, so it is not the suit for June. You get wet in a wetsuit, that is the design, and if you want to stay dry in near-freezing water you are talking about a drysuit, which is a whole different tool and a whole different bank account. The honest place for this suit sits on the fence where I live: spring and fall shore water, right at sixty to sixty-five, where a well-fitted 7mm outlasts every layer I used to carry.

And everything depends on that fit, not on thickness alone. Thick neoprene does nothing for you if it bags at the small of your back. You have to bend, reach up, sit, reach for a dump valve, all before the plastic. A suit that fits everywhere at once is the one that returns the season; please think of the half of this that is measuring and not speccing specifications.

What I didn't tell you yet, the part that makes me grin: the cold months were the best dives all the year in disguise. After September every quarry and pier calms down, the water clears, and the summer boats are back to their moorings with the whole edge to yourselves. Some of my longest, quietest dives now come on days I used to spend raking. I did not just survive a season I used to skip. I ended up liking it better.

Two pieces I can point you at if you want more than my word on it. My long-term review of the Mares M-Flex 7mm covers the zippers, the sleeves and the day-to-day after a real length of cold dives. And I put together a list of ten reasons a 7mm suit genuinely extends a season. Both go deeper on the same ideas than I can here.

What I'd Tell You If We Were Sitting at My Kitchen Table

Here is the plain talk I would give you across the tabletop while the coffee cools. If the numbers sixty or seventy have been stealing your Septembers and Octobers, do what I did not do for two winters, and get your fit looked at before you accept the loss. Then give a serious 7mm, the Mares, an honest try in your own size, and do not judge it until you have reached up, bent, and moved in it. It is big and it fights to get on, I will not dress that up. I put up with it because the trade is the season, and nobody checks the calendar at sixty feet. The fall and the late spring keep turning out days I used to forfeit, and every one of them so far has been worth the squeeze.