Sea to Summit has several active deals running right now, with 10% off your first purchase standing as the main offer for new customers. Depending on what you're buying and your basket size, different offers will save you more money.
If you're shopping with a smaller basket under $50, the 10% off first purchase deal is your best bet, especially if you're a new customer. This applies to your entire order regardless of spend level, so it's worth taking.
If you're buying essentials or smaller items and your order totals between $50 and $99, you're at the sweet spot where free shipping on orders $50 and above kicks in. Compare the two: the 10% first purchase discount on a $75 order saves you around $7.50, while free shipping saves you the actual shipping cost. Check your cart total and the estimated shipping fee to see which works better for you.
If you're targeting one of Sea to Summit's featured items, you might find a better saving. The Extra 10% off the Flame Ultralight Women's Sleeping Bag, the 25% off the Alto Semi-Free Standing Ultralight Tent, and the 25% off the Telos Bikepacking TR2 tent are all active. On a $300 Alto tent, for example, that's $75 in savings versus $30 with the first purchase offer. If the item you want is on this list, the product-specific discount almost certainly beats the general 10% first purchase deal.
If you're spending $100 or more without a specific product deal available, the free shipping offer becomes less competitive against the 10% first purchase discount (which saves you $10 on a $100 basket), unless your shipping cost exceeds that figure.
Only one offer applies at checkout, so add your items to your cart and check the discount each option would give you. Compare the actual dollar amount saved by each available offer and choose the one that reduces your total the most.