Your comfort can range from too cold to too hot within minutes ― and everything will get wet ― so wear lightweight synthetic fibers that have a wide temperature range and dry quickly. Here's a packing list.
• Snug-fitting hat with a brim
• Waterproof, sweatproof sunscreen
• Sunglasses with a strap
• Short-sleeved top
• Loose-fitting, long-sleeved top for layering
• Knee-length shorts, or pants
• Waterproof sandals with heel straps (no flip-flops), aqua shoes, or old sneakers
• Wetsuit and splash jacket if it's really cold (many outfitters will provide these when conditions warrant them)
• Waterproof disposable camera
• Waterproof watch (but leave rings and other jewelry behind to avoid blisters or loss)