Have tow line, rigged and ready for use. Carry a safety helmet for rough seas. Essential are drogues and sea chutes, some people also carry anchors. The type of clothing you wear when paddling makes a big difference. Your outer garments should be waterproof and windproof, such as a drysuit or a wetsuit, your inside layers should be light clothing of wool or polypropylene.
Footwear can be rubber boots or wet suit booties.
For cooler, rainy weather you will need pogies or gloves. Every last detail should be planned, before you start out on your sea kayaking trip. Whether paddling with a small group or a larger one, pre-trip daily planning should be a must. That way everyone knows where to go and where to meet, should the group be separately for any reason. Learn all you can about the waters you plan to paddle and discuss your trip, listen to weather forecasts, pay heed to the winds and be completely aware of your sea kayaking experience and knowledge.